Multiple choice

The ratio of age of A and B. 2 year ago was 9 : 5. After 1 year this ratio become 7 : 4. What is the presentage of B. 2 वर्ष पूर्व A तथा B की आयु का अनुपात 9 : 5 था। एक वर्ष बाद यह अनुपात 7 : 4 हो गया। B की वर्तमान आयु ज्ञात कीजिए?

  1. 48 year/वर्ष

  2. 47 year/वर्ष

  3. 38 year/वर्ष

  4. 58 year/वर्ष
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B Correct answer
Explanation

Let present ages be A and B. Two years ago: (A-2)/(B-2) = 9/5, so 5A - 10 = 9B - 18, giving 5A = 9B - 8. After one year: (A+1)/(B+1) = 7/4, so 4A + 4 = 7B + 7, giving 4A = 7B + 3. Solving: From 5A = 9B - 8, A = (9B - 8)/5. Substituting in 4A = 7B + 3: 4(9B - 8)/5 = 7B + 3, giving 36B - 32 = 35B + 15, so B = 47. Present age of B is 47 years.

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