Billy's age is
34 his sister's age now. 12 years ago, his age was
35 that of his sister's. How old is Billy now?
| |
Billy |
Billy's sister |
Difference |
| Before |
3x1 =
3 u |
5x1 =
5 u |
2x1 =
2 u |
| Change |
+ 12 |
+ 12 |
|
| After |
3x2 =
6 u |
4x2 =
8 u |
1x2 =
2 u |
The difference in the age between Billy and Billy's sister remains unchanged. Make the difference in age the same. LCM of 2 and 1 is 2.
Increase in the age of Billy
= 6 u - 3 u
= 3 u
3 u = 12
1 u = 12 ÷ 3 = 4
Billy's age now
= 6 u
= 6 x 4
= 24
Answer(s): 24
