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SSC Selection Post 2019 PYQ — Question 64

SSC Selection Post - Matriculation Level 2019 - 15 Oct 2019 • Quantitative Aptitude • Q64

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Four years ago, the ratio of the ages (in years) of A and B was 8:9. The ratio of their ages, 8 years from now, will be 11:12. What is the sum of their present ages in years?

 

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Correct answer: D

Explanation

The correct answer is Option 4 i.e. 76.

Let present ages be x and y

From 4 years ago:

x−4y−4=89⇒9x−8y=4(1)\frac{x - 4}{y - 4} = \frac{8}{9} \Rightarrow 9x - 8y = 4 \quad \text{(1)}

From 8 years later :

x+8y+8=1112⇒12x−11y=−8(2)\frac{x + 8}{y + 8} = \frac{11}{12} \Rightarrow 12x - 11y = -8 \quad \text{(2)}

Multiply (1) by 12 , so 108x − 96y = 48

Multiply (2) by 9 , so 108x − 99y = −72

Subtract:

3y = 120 ⇒ y = 40, x = 36

⇒x + y = 76