The present age ratio of X to Y's

Solution

ATQ, Let present age of 'X' be '7x' years and age of Y' 5 years ago from now be '9x' years. So, present age of 'Y' = (9x + 5) years 10 years hence from now, age of 'Y' = 9x + 5 + 10 = (9x + 15) years 10 years hence from now, age of 'Z' = 115 - (9x + 15) = (100 - 9x) years Present age of 'Z' = 100 - 9x - 10 = (90 - 9x) years ATQ; (90 - 9x) = 7x × (9/7) = 9x Or, 90 = 18x Or, x = (90/18) = 5 So, required sum = 7x + 9x + 5 = 16 × 5 + 5 = 85