Adam's age is a multiple of 6 this year.
His age next year will be multiple of 5.
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 5?
(a)
Multiples of 6 (between 20 and 30): 24, 30
Multiples of 6 (+1): 13, 19, 25, 31
Multiples of 5: 20, 25, 30
Adam's age next year: 25Adam's age this year: 24Multiples of 7: 14, 21, 28
Adam's age when it becomes a multiple of 7 = 28
Number of years' time when Adam's age will be a multiple of 7
= 28 - 24
= 4
(b)
Multiple of 5: 10, 15, 20
Least number of years ago when Adam's age was a multiple of 5
= 24 - 20
= 4
Answer(s): (a) 4; (b) 4