Question

69. Proportion of two brother's ages 10 years back was 3:5. After 10 years, this
proportion will be 7: 9. What is the sum of their ages today?
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Answer 1

Answer:

Answer: 60 is the answer.

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Observe that within 20 years of timespan, their age's ratio increased by just 4 in both numerator and denominator. 20/4=5.

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That means, 10 year ago from now, there ages were 3x5 and 5x5 (15 years and 25 years).

Thus, their ages after 10 year from now will be 15+20 and 25+20 (35 years and 45 years).

If you want to cross- verify, then observe that their ages are in the right mentioned ratio only.

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So, their current age will 15+10= 25 years and 25+10=35 years.

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Sum of the ages will be 25+35= 60.