In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
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Question: Problem: at what rate percent per annum will the simple interest on a sum of money be 4 / 5 of the amount in 10 years ? 
Options: a ) 4 % , b ) 7 % , c ) 8 % , d ) 3 % , e ) 1 %

Answer: c


Question: Problem: a can complete a certain job in 19 days . b is 90 % more efficient than a . in how many days can b complete the same job ? 
Options: a ) 6 , b ) 6.25 , c ) 7 , d ) 7.5 , e ) 10

Answer: e


Question: Problem: if the radius of a circle is decreased by 50 % , find the percentage decrease 
Options: a ) 22 , b ) 099 , c ) 75 , d ) 26 , e ) 18

Answer:
c