Mrs Pang is 53 years old and her son is 11 years old now. In how many years' time will Mrs Pang be thrice as old as her son?
| |
Mrs Pang |
Her son |
Difference |
| Before |
53 |
11 |
42 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Mrs Pang and her son remains unchanged.
Difference in their age at first
= 53 - 11
= 42
Difference in their age in the end
= 3 u - 1 u
= 2 u
2 u = 42
1 u = 42 ÷ 2 = 21
Number of years time that Mrs Pang will be thrice as old as her son
= 1 u - 11
= 21 - 11
= 10
Answer(s): 10
