TASK DEFINITION: In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
PROBLEM: Problem: find the principle on a certain sum of money at 5 % per annum for 3 1 / 5 years if the amount being rs . 870 ? 
Options: a ) rs . 700 , b ) rs . 780 , c ) rs . 750 , d ) rs . 1000 , e ) none of these

SOLUTION: c

PROBLEM: Problem: average age of students of an adult school is 42 years . 120 new students whose average age is 32 years joined the school . as a result the average age is decreased by 4 years . find the number of students of the school after joining of the new students . 
Options: a ) 1200 , b ) 120 , c ) 360 , d ) 200 , e ) none of these

SOLUTION: d

PROBLEM: Problem: if the average ( arithmetic mean ) of a and b is 40 and the average of b and c is 60 , what is the value of c − a ? 
Options: a ) 25 , b ) 40 , c ) 90 , d ) 140 , e ) it can not be determined from the information given .

SOLUTION:
b