What is 9/15 plus 4/5? (Answer: 7/5)

Exact Answer

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Problem: What is 9/15 plus 4/5?
Formula / Expression: 9/15 + 4/5
Final Answer: 1 2/5 (7/5)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
Notice that 15 is an exact multiple of 5 (5 × 3 = 15). The Least Common Denominator (LCD) is simply 15, meaning we only need to scale one fraction.
Working: LCD(15, 5) = 15

Step 2: Convert to Equivalent Fractions with Common Denominator 15
Multiply the numerator and denominator of 9/15 by 1, and multiply the numerator and denominator of 4/5 by 3 so both fractions share the common base 15.
Working: 9 × 1/15 × 1 = 9/15 and 4 × 3/5 × 3 = 12/15

Step 3: Add the Numerators
Now add the numerators (9 + 12 = 21) and keep the common denominator 15 unchanged.
Working: 9 + 12/15 = 21/15

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 21 and 15, which is 3. Divide both the numerator and denominator by 3.
Working: 21 ÷ 3/15 ÷ 3 = 7/5

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (7) is greater than the denominator (5), divide 7 by 5: it goes in 1 whole time(s) with a remainder of 2, giving the mixed number 1 2/5.
Working: 7/5 = 1 2/5

Step 6: Decimal & Percentage Representation
Dividing the numerator 7 by denominator 5 yields an exact terminating decimal of 1.4 (or 140%).
Working: 7 ÷ 5 = 1.4 (140%)

Key Values:
- Simplified Fraction: 7/5
- Mixed Number Form: 1 2/5
- Decimal Value: 1.4
- Percentage: 140%

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9/15 + 4/5 = 7/5

Simplified Fraction

7/5

Mixed Number

1 2/5

Decimal Value

1.4

Percentage

140%

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Step-by-Step Solution: 9/15 + 4/5

Step 1

Find the Least Common Denominator (LCD)

Notice that 15 is an exact multiple of 5 (5 × 3 = 15). The Least Common Denominator (LCD) is simply 15, meaning we only need to scale one fraction.

LCD(15, 5) = 15

Step 2

Convert to Equivalent Fractions with Common Denominator 15

Multiply the numerator and denominator of 9/15 by 1, and multiply the numerator and denominator of 4/5 by 3 so both fractions share the common base 15.

9 × 1/15 × 1 = 9/15 and 4 × 3/5 × 3 = 12/15

Step 3

Add the Numerators

Now add the numerators (9 + 12 = 21) and keep the common denominator 15 unchanged.

9 + 12/15 = 21/15

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 21 and 15, which is 3. Divide both the numerator and denominator by 3.

21 ÷ 3/15 ÷ 3 = 7/5

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (7) is greater than the denominator (5), divide 7 by 5: it goes in 1 whole time(s) with a remainder of 2, giving the mixed number 1 2/5.

7/5 = 12/5

Step 6

Decimal & Percentage Representation

Dividing the numerator 7 by denominator 5 yields an exact terminating decimal of 1.4 (or 140%).

7 ÷ 5 = 1.4 (140%)

Visual Representation

The diagram below illustrates 9/15 plus 4/5 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`7/5`
Mixed Number Form	`1 2/5`
Decimal Form	`1.4`
Percentage	`140%`

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Frequently Asked Questions

What is 9/15 plus 4/5 as a fraction?

9/15 + 4/5 in simplest fraction form is 7/5 (or 1 2/5 as a mixed number).

What is 9/15 plus 4/5 as a decimal?

9/15 + 4/5 converted to a decimal is 1.4.

What is 9/15 plus 4/5 as a percentage?

9/15 + 4/5 expressed as a percentage is 140%.

How do you write 9/15 plus 4/5 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 7/5 can be written as the mixed number 1 2/5.

Does 9/15 plus 4/5 result in a terminating or repeating decimal?

It results in an exact terminating decimal (1.4) because the denominator in simplest terms contains only prime factors 2 and/or 5.