Answer:
Plug x-7 in for y, in the bottom equation.
x - 7 = 2 + 2x - 4
x - 7 = 2x - 2
x = 2x + 5
-x = 5
x = -5
Step-by-step explanation:
r-5r-6s+8s-15
-4r+2s-15
= 2s-4r-15
Answer: a = 
We want to isolate a. Add both sides by 2. Then we get u + 2 = 2a. To get just a, we can divide by 2 to get (u+2)/2.
Hope that helped,
-sirswagger21
Complements are numbers that add 90. Since one is 57, the other has to add to 57. So 33 would add with 57 to get 90.