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'.

Problem: john makes $ 65 a week from his job . he earns a raise andnow makes $ 70 a week . what is the % increase ?
Options: a ) 7.69 % , b ) 16.66 % , c ) 17.8 % , d ) 19 % , e ) 21 %
a

Problem: by selling 10 pencils for a rupee a man loses 15 % . how many for a rupee should he sell in order to gain 15 % ?
Options: a ) 8.39 , b ) 6.39 , c ) 7.39 , d ) 9.39 , e ) 2.39
c

Problem: a portion of the 85 % solution of chemicals was replaced with an equal amount of 20 % solution of chemicals . as a result , 40 % solution of chemicals resulted . what part of the original solution was replaced ?
Options: a ) 5 / 13 , b ) 6 / 13 , c ) 9 / 13 , d ) 13 / 9 , e ) 13 / 6
c