The task is to generate the correct answer for a given math problem.

Ex Input:
Problem: a man purchased earphone on friday . but he forgot how much it cost . the data he have are mean expenditure of all 7 days is 500 . expenditure on mon , tue , wed , thurs , sat , sun are 450600 , 400500 , 550300 . on friday he purchased 3 things one earphone , one pen and one notebook . pen cost 30 and notebook cost 50 . then what is cost of earphone ?

Ex Output:
620


Ex Input:
Problem: a , b and c start a business each investing 20,000 . after 6 months a withdrew 5000 , b withdrew 4000 and c invests 6000 more . at the end of the year , a total profit of 67,600 was recorded . find the share of b .

Ex Output:
21,600


Ex Input:
Problem: how many positive integers less than 5,000 are evenly divisible by neither 14 nor 21 ?

Ex Output:

4,34