A man's age is 125% of what he was 10 years ago, but 83 1/3 % of what…

83\(\frac{1}{3}\)% = \(\frac{5}{6}\)

125% = \(\frac{5}{4}\)

10yr. ago    :      Present      :    10 Years after

      4           :         5

                             5           :             6      

      4           :         5           :             6

Now,

Difference = 1R in every 10 years

Therefore, 1R =  10 years

A's present age = 5 × 10 = 50 years