Perry's current age is 7 times as old as Ken's age years ago. Today, Ken's age is Perry's age the same number of years ago. How old is Ken's age now if the total of their current age is 77?
| |
Perry |
Ken |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
7 u |
1 p |
7 u - 1 p |
77 |
Total age of Perry and Ken today = 7 u + 1 p
7 u + 1 p = 77 --- (1)
The difference in Perry's age and Ken'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 = 77
7 u + 4 u = 77
11 u = 77
1 u = 77 ÷ 11 = 7
Perry's age now
= 77 - 7 u
= 77 - 7 x 7
= 77 - 49
= 28
Answer(s): 28
