Adam's age is a multiple of 4 this year.
His age next year will be multiple of 3.
Adam's age is between 20 and 30.
- In how many years' time will Adam's age be a multiple of 7?
- How many years ago was Adam's age a multiple of 8?
(a)
Multiples of 4 (between 20 and 30): 20, 24, 28
Multiples of 4 (+1): 13, 17, 21, 25, 29
Multiples of 3: 21, 24, 27, 30
Adam's age next year: 21Adam's age this year: 20Multiples of 7: 14, 21, 28
Adam's age when it becomes a multiple of 7 = 21
Number of years' time when Adam's age will be a multiple of 7
= 21 - 20
= 1
(b)
Multiple of 8: 16
Least number of years ago when Adam's age was a multiple of 8
= 20 - 16
= 4
Answer(s): (a) 1; (b) 4