They are $0.2 each
10/50=.20
15 I helped someone with this question already so I know its right
x + 4 = 15
- 4 -4
x = 11
You would subtract 4 because you need to isolate the x to get the value of x. You would subtract it to both sides because whatever you do on one side, you have to do it to the other side.
