What is 3/7 plus 4/5? (Answer: 43/35)

Exact Answer

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Problem: What is 3/7 plus 4/5?
Formula / Expression: 3/7 + 4/5
Final Answer: 1 8/35 (43/35)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 7 and 5 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 7 × 5 = 35.
Working: LCD(7, 5) = 35

Step 2: Convert to Equivalent Fractions with Common Denominator 35
Multiply the numerator and denominator of 3/7 by 5, and multiply the numerator and denominator of 4/5 by 7 so both fractions share the common base 35.
Working: 3 × 5/7 × 5 = 15/35 and 4 × 7/5 × 7 = 28/35

Step 3: Add the Numerators
Now add the numerators (15 + 28 = 43) and keep the common denominator 35 unchanged.
Working: 15 + 28/35 = 43/35

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 43 and 35 is 1, confirming that 43/35 cannot be reduced further—it is already in its simplest irreducible form.
Working: 43/35

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (43) is greater than the denominator (35), divide 43 by 35: it goes in 1 whole time(s) with a remainder of 8, giving the mixed number 1 8/35.
Working: 43/35 = 1 8/35

Step 6: Decimal & Percentage Representation
Dividing the numerator 43 by denominator 35 produces a repeating decimal (approximately 1.228571, or 122.8571%).
Working: 43 ÷ 35 = 1.228571 (122.8571%)

Key Values:
- Simplified Fraction: 43/35
- Mixed Number Form: 1 8/35
- Decimal Value: 1.228571
- Percentage: 122.8571%

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Solved with FractionsCalc:
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3/7 + 4/5 = 43/35

Simplified Fraction

43/35

Mixed Number

1 8/35

Decimal Value

1.228571

Percentage

122.8571%

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Step-by-Step Solution: 3/7 + 4/5

Step 1

Find the Least Common Denominator (LCD)

The denominators 7 and 5 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 7 × 5 = 35.

LCD(7, 5) = 35

Step 2

Convert to Equivalent Fractions with Common Denominator 35

Multiply the numerator and denominator of 3/7 by 5, and multiply the numerator and denominator of 4/5 by 7 so both fractions share the common base 35.

3 × 5/7 × 5 = 15/35 and 4 × 7/5 × 7 = 28/35

Step 3

Add the Numerators

Now add the numerators (15 + 28 = 43) and keep the common denominator 35 unchanged.

15 + 28/35 = 43/35

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 43 and 35 is 1, confirming that 43/35 cannot be reduced further—it is already in its simplest irreducible form.

43/35

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (43) is greater than the denominator (35), divide 43 by 35: it goes in 1 whole time(s) with a remainder of 8, giving the mixed number 1 8/35.

43/35 = 18/35

Step 6

Decimal & Percentage Representation

Dividing the numerator 43 by denominator 35 produces a repeating decimal (approximately 1.228571, or 122.8571%).

43 ÷ 35 = 1.228571 (122.8571%)

Visual Representation

The diagram below illustrates 3/7 plus 4/5 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`43/35`
Mixed Number Form	`1 8/35`
Decimal Form	`1.228571`
Percentage	`122.8571%`

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Frequently Asked Questions

What is 3/7 plus 4/5 as a fraction?

3/7 + 4/5 in simplest fraction form is 43/35 (or 1 8/35 as a mixed number).

What is 3/7 plus 4/5 as a decimal?

3/7 + 4/5 converted to a decimal is 1.228571.

What is 3/7 plus 4/5 as a percentage?

3/7 + 4/5 expressed as a percentage is 122.8571%.

How do you write 3/7 plus 4/5 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 43/35 can be written as the mixed number 1 8/35.

Does 3/7 plus 4/5 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.228571...) because the denominator contains prime factors other than 2 and 5.