The ratio of Ben's age to Carl's age is 5 : 2. Last year, their average age was 20. How old will Carl be in 5 years' time?
| |
Ben |
Carl |
Total |
| Before |
5 u - 1 |
2 u - 1 |
40 |
| Change |
+ 1 |
+ 1 |
|
| After |
5 u |
2 u |
42 |
Total age of Ben and Carl this year
= 5 u + 2 u
= 7 u
Total age of Ben and Carl this year
= 2 x 20 + 1 + 1
= 40 + 2
= 42
7 u = 42
1 u = 42 ÷ 7 = 6
Carl's age in 5 years' time
= 2 u + 5
= 2 x 6 + 5
= 12 + 5
= 17
Answer(s): 17
