math word problem

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Scooby Scooby
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math word problem

Five years ago Ben was 2/3 as old as Kris. Ten years from now he will be 5/6 as old as Kris. How old are Ben and Kris now?
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Re: math word problem

k = Kris' age 5 years ago
(2/3)k = Ben's age 5 years ago

k + 15 = Kris' age 10 years from now   ← added 15 onto age 5 years ago
(2/3)k + 15 = Ben's age 10 years from now   ← added 15 onto age 5 years ago

(2/3)k + 15 = (5/6)(k + 15)   ← ten years from now, Ben will be 5/6 as old as Kris
4k + 90 = 5(k + 15)   ← multiplied entire equation by 6, eliminating fractions
4k + 90 = 5k + 75   ← distributed
k = 15   ← subtracted 4k and 75
(2/3)k = 10   ← substituted 15 for k

Kris is 15
Ben is 10

- Proof