Adam's age is a multiple of 10 this year.
His age 9 years ago was a multiple of 3.
- What is Adam's age this year?
- What was Adam's age 7 years ago?
- What is Adam's age 7 years later?
Multiple of 10: 10, 20, 30
Multiple of 10 (-9): 1, 11, 21
Multiple of 3: 3, 6, 9, 12, 15, 18, 21
21 appears in both the multiples of 10 (-9) and the multiples of 3.
Adam's age 9 years ago = 21
(a) Adam's age this year = 30
(b) Adam's age 7 year ago = 30 - 7 = 23
(c) Adam's age 10 years later = 30 + 7 = 37
Answer(s): (a) 30; (b) 23; (c) 37