The ratio of Harry's age to Luis's age is 3 : 1. Last year, their average age was 19. How old will Luis be in 7 years' time?
| |
Harry |
Luis |
Total |
| Before |
3 u - 1 |
1 u - 1 |
38 |
| Change |
+ 1 |
+ 1 |
|
| After |
3 u |
1 u |
40 |
Total age of Harry and Luis this year
= 3 u + 1 u
= 4 u
Total age of Harry and Luis this year
= 2 x 19 + 1 + 1
= 38 + 2
= 40
4 u = 40
1 u = 40 ÷ 4 = 10
Luis's age in 7 years' time
= 1 u + 7
= 1 x 10 + 7
= 10 + 7
= 17
Answer(s): 17
