Riordan's current age is 7 times as old as Billy's age years ago. Today, Billy's age is Riordan's age the same number of years ago. How old is Riordan's age now if the total of their current age is 88?
| |
Riordan |
Billy |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
7 u |
1 p |
7 u - 1 p |
88 |
Total age of Riordan and Billy today = 7 u + 1 p
7 u + 1 p = 88 --- (1)
The difference in Riordan's age and Billy's age remains the same.
7 u - 1 p = 1 p - 1 u
7 u + 1 u = 1 p + 1 p
8 u = 2 p
4 u = 1 p
Substitute 1 p = 4 u into (1).
7 u + 1 p = 88
7 u + 4 u = 88
11 u = 88
1 u = 88 ÷ 11 = 8
Riordan's age now
= 7 u
= 7 x 8
= 56
Answer(s): 56
