SOLUTION: Kevin is three times as old as Bob. Three years ago the sum of their ages was 22yr. How old is each now?

Question 125803: Kevin is three times as old as Bob. Three years ago the sum of their ages was 22yr. How old is each now?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Write an equation for each statement:
:
"Kevin is three times as old as Bob."
k = 3b
:
Three years ago, their ages;
(k-3) and (b-3), right?
:
"Three years ago the sum of their ages was 22yr."
(k-3) + (b-3) = 22
:
k - 3 + b - 3 = 22
:
k + b - 6 = 22
:
k + b = 22 + 6
:
k + b = 28
:
How old is each now?
:
Substitute 3b for k, find b
3b + b = 28
:
4b = 28
b =
b = 7 yrs old is Bob
then
3(7) = 21 yrs old is Kevin
:
:
Check our solution using the statement:
"Three years ago the sum of their ages was 22yr. "
(21-3) + (7-3) =
18 + 4 = 22; confirms our solution
:
Not that hard, do you think?
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