SOLUTION: Hi, I need help with a math problem: The ratio between the ages of John and David is 6:5. In 7 years time the ratio between their ages will be 7:6. How old are they today?

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Hi, I need help with a math problem: The ratio between the ages of John and David is 6:5. In 7 years time the ratio between their ages will be 7:6. How old are they today?       Log On


   

Question 1005487: Hi,
I need help with a math problem:
The ratio between the ages of John and David is 6:5. In 7 years time the ratio between their ages will be 7:6. How old are they today?
Thanks for the help.
- E.S.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
j and d for ages of JOHN and DAVID


ratio between the ages of John and David is 6:5.
j%2Fd=6%2F5
j=6d%2F5


In 7 years time the ratio between their ages will be 7:6
%28j%2B7%29%2F%28d%2B7%29=7%2F6
6%28j%2B7%29=7%28d%2B7%29
6j%2B42=7d%2B49
6j-7d=49-42=7

Substitute for j in the 7-years equation.
6%286d%2F5%29-7d=7
36d%2F5-7d=7
36d-35d=35
highlight%28d=35%29

JOHN'S DAVID'S AGE
j=6d%2F5
j=6%2A35%2F5
highlight%28j=42%29


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fixed mistake