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: the sum of all the digits of the integers from 18 to 21 inclusive is 24 ( 1 + 8 + 1 + 9 + 2 + 0 + 2 + 1 = 24 ) . what is the sum t of all the digits of the integers from 0 to 99 inclusive ? 
Options: a ) 450 , b ) 810 , c ) 900 , d ) 1000 , e ) 1100
c

Problem: a student chose a number , multiplied it by 8 , then subtracted 138 from the result and got 102 . what was the number he chose ? 
Options: a ) 30 , b ) 120 , c ) 130 , d ) 140 , e ) 150
a

Problem: if ( a – b ) is 15 more than ( c + d ) and ( a + b ) is 3 less than ( c – d ) , then ( a – c ) is : 
Options: a ) 6 , b ) 2 , c ) 3 , d ) 4 , e ) 5

a