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3/4 of number is 15 work out 4/5’s of the number

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4 votes

Answer:

16

Explanation:

If 3/4 of a number is 15, we first want to calculate what 4/4 is (the original number).

to do this, first, we divide 15 by 3 to calculate 1/4 of the number.

(let me know if this step doesn't make sense)

15 ÷ 3 = 5

then multiply by 4 to find 4/4 of the number

5 × 4 = 20

therefore the full number is 20

we can verify this by quickly calculating 3/4 of 20 by multiplying by 0.75 (let me know if that doesn't make sense either)

20 x 0.75 = 15

no2 to calculate 4/5 of 20, we can either divide by 5 to find 1/5 and then multiply that by 4 to find 4/5, or we can more simply calculate 4/5 as a decimal and multiply that decimal by 20.

the long(er) way:

20 ÷ 5 = 4 (1/5 of 20)

4 x 4 = 16 (4 x 1/5 of 20)

therefore 4/5 of the number = 16

the short(er) way:

4/5 = 0.8 (this is the rate)

0.8 x 20 = 16

therefore 4/5 of the number = 16

hope this helps :)

let me know if there's anything you don't understand

User Apires
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