Adam's age is a multiple of 7 this year.
His age 3 years ago was a multiple of 10.
Adam's age is between 60 and 70.
- In how many years' time will Adam's age be a multiple of 10?
- How many years ago was Adam's age a multiple of 10?
(a)
Multiple of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63
Multiple of 7 (-3): 4, 11, 18, 25, 32, 39, 46, 53, 60
Multiples of 10: 10, 20, 30, 40, 50, 60
Adam's age this year = 63
Multiples of 10: 10, 20, 30, 40, 50, 60, 70
Number of years' time when Adam will be a multiple of 10
= 70 - 63
= 7
(b)
Multiples of 10: 10, 20, 30, 40, 50, 60
Least number of years ago when Adam's age was a multiple of 10
= 63 - 60
= 3
Answer(s): (a) 7; (b) 3