Billy's current age is 7 times as old as Albert's age years ago. Today, Albert's age is Billy's age the same number of years ago. How old is Albert's age now if the total of their current age is 22?
| |
Billy |
Albert |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
7 u |
1 p |
7 u - 1 p |
22 |
Total age of Billy and Albert today = 7 u + 1 p
7 u + 1 p = 22 --- (1)
The difference in Billy's age and Albert'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 = 22
7 u + 4 u = 22
11 u = 22
1 u = 22 ÷ 11 = 2
Billy's age now
= 22 - 7 u
= 22 - 7 x 2
= 22 - 14
= 8
Answer(s): 8
