Justin's age is
25 his sister's age now. In 20 years' time, his age will be
35 that of his sister's. How old is Justin now?
| |
Justin |
Justin's sister |
Difference |
| Before |
2x2 =
4 u |
5x2 =
10 u |
3x2 =
6 u |
| Change |
+ 20 |
+ 20 |
|
| After |
3x3 =
9 u |
5x3 =
15 u |
2x3 =
6 u |
The difference in the age between Justin and Justin's sister remains unchanged. Make the difference in age the same. LCM of 3 and 2 is 6.
Increase in the age of Justin
= 9 u - 4 u
= 5 u
5 u = 20
1 u = 20 ÷ 5 = 4
Justin's age now
= 4 u
= 4 x 4
= 16
Answer(s): 16
