Glen's current age is 9 times as old as Bobby's age years ago. Today, Bobby's age is Glen's age the same number of years ago. How old is Bobby's age now if the total of their current age is 56?
| |
Glen |
Bobby |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
9 u |
1 p |
9 u - 1 p |
56 |
Total age of Glen and Bobby today = 9 u + 1 p
9 u + 1 p = 56 --- (1)
The difference in Glen's age and Bobby's age remains the same.
9 u - 1 p = 1 p - 1 u
9 u + 1 u = 1 p + 1 p
10 u = 2 p
5 u = 1 p
Substitute 1 p = 5 u into (1).
9 u + 1 p = 56
9 u + 5 u = 56
14 u = 56
1 u = 56 ÷ 14 = 4
Glen's age now
= 56 - 9 u
= 56 - 9 x 4
= 56 - 36
= 20
Answer(s): 20
