Rael's current age is 7 times as old as Andy's age years ago. Today, Andy's age is Rael's age the same number of years ago. How old is Andy's age now if the total of their current age is 99?
| |
Rael |
Andy |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
7 u |
1 p |
7 u - 1 p |
99 |
Total age of Rael and Andy today = 7 u + 1 p
7 u + 1 p = 99 --- (1)
The difference in Rael's age and Andy'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 = 99
7 u + 4 u = 99
11 u = 99
1 u = 99 ÷ 11 = 9
Rael's age now
= 99 - 7 u
= 99 - 7 x 9
= 99 - 63
= 36
Answer(s): 36
