Tim's auntie is 3 times as old as him. His auntie will be 40 years old in 4 years' time. In how many years' time will Tim's age be 70% that of his auntie's?
| |
Tim's auntie |
Tim |
Difference |
Before
(now) |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
| Change 1 |
+ 4 |
+ 4 |
|
| After 1 |
40 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
10x2 =
20 u |
7x2 =
14 u |
3x2 =
6 u |
70% =
70100 =
710 Tim's auntie : Tim = 10 : 7
The difference in age between Tim's auntie and Tim always remains the same. Make the difference in age between Tim's auntie and Tim the same. LCM of 2 and 3 is 6.
9 u + 4 = 40
9 u = 40 - 4
9 u = 36
1 u = 36 ÷ 9 = 4
Number of years' time when Tim's age will be 70% that of his auntie's
= 20 u - 40
= 20 x 4 - 40
= 80 - 40
= 40
Answer(s): 40
