The average age of husband, wife and child 7 years ago was 42 years and that of wife and child 9 years ago was 36 years. The present age of the husband is:

57

ATQ

Sum of age of husband, wife and child, 7 years ago = 42 × 3 = 126

Sum of their present age = 126 + 21 = 147

Sum of age of wife and child, 9 years ago = 36 × 2 = 72

Sum of present age of wife and child = 72 + 18 = 90

Present age of husband = 147 - 90 = 57 years