The ratio of Oscar's age to Cody's age is 5 : 3. Next year, their average age will be 21. How old will Oscar be in 11 years' time?
| |
Oscar |
Cody |
Total |
| Before |
5 u |
3 u |
40 |
| Change |
+ 1 |
+ 1 |
|
| After |
5 u + 1 |
3 u + 1 |
42 |
Total age of Oscar and Cody this year
= 5 u + 3 u
= 8 u
Total age of Oscar and Cody this year
= 2 x 21 - 1 - 1
= 42 - 2
= 40
8 u = 40
1 u = 40 ÷ 8 = 5
Oscar's age in 11 years' time
= 5 u + 11
= 5 x 5 + 11
= 25 + 11
= 36
Answer(s): 36
