You can put this solution on YOUR website! Let Billy's age be b years and
let Joe's age be J years.
The sum of the ages of Billy and Joe is 25.
That means b + j = 25 -------(1)
Triple Billy's age plus 7 times Joe's age is 99 years.
[Triple Billy's age means 3b and 7 times Joe's age is 7j]
3b + 7j = 99 -------(2)
Putting b = (25 - j)(from (1)) in (2)
we get 3(25 - j) + 7j = 99
75 - 3j + 7j = 99
75 + 4j = 99
4j = 99 - 75
4j = 24
Dividing by 4,
which means j = 6 that is Joe's age is 6 years
and as Billy's and Joe's ages add up to 25
this gives b = 25 - j = 25 - 6 = 19 that is Billy's age is 19 years
Answer: Billy's age = 19 years and Joe's age = 6 years
Verification:
3 times Billy's age plus 7 times Joe's age should be 99 years
3X19 + 7X6 = 57 + 42 = 99 which is correct
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