Answer:
A: 5
28-3x=13 You have to get rid of 28, so you
-28 -28 subtract 28 from both sides. 28-28 and 13-28
-3x=-15 Now you have to divide both sides by -3
-3x = -15 So, on the left side, you get 1 or just x, -3 -3 and on the right side 5
x=5
I really hope that makes sense
