15 dvds in all. there are 7 comedy dvds. 4 more drama dvds than horror dvds.
comedy dvds=
drama dvds=
horror dvds=
how do i solve this? i need to explain this to my 4th grader and i can't even figure it out and i'm his mother. .

Comedy = 7; Horror = x ; Drama = x+4 ;
15 = 7 + x + x + 4;
15 = 7 + 2*x +4;
15 - 7 -4 = 2*x ;
4 = 2*x;
x = 4 : 2;
x = 2 ;  ---Horror
2 + 4 = 6    ---Drama

Comedy DVDs=7
Drama DVDs + Horror DVDs = 15 - 7 = 8

You know that the difference between the amount of Drama DVDs and Horror DVDs is 4 and, from sum above, you now know that they add up to 8.  The two numbers are 2 and 6. 

Comedy DVDs = 7
Drama DVDs = 6
Horror DVDs = 2

To check, add them together.  

That she received $100