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: how many two - digit numbers yield a remainder of 1 when divided by both 6 and 15 ? 
Options: a ) 0 , b ) 1 , c ) 2 , d ) 3 , e ) 4
c

Problem: a sum of money lent out at s . i . amounts to a total of $ 480 after 2 years and to $ 680 after a further period of 5 years . what was the initial sum of money that was invested ? 
Options: a ) $ 360 , b ) $ 380 , c ) $ 400 , d ) $ 420 , e ) $ 440
c

Problem: you collect pens . suppose you start out with 5 . mike gives you another 20 pens . since her father makes pens , cindy decides to double your pens . since you ' re nice , you give sharon 19 pens . how many pens do you have at the end ? 
Options: a ) 39 , b ) 40 , c ) 31 , d ) 42 , e ) 43

c