Answer:
Step-by-step explanation:
-3(r - 7) - 4(-7r - 8) = 28
-3*r - (-3)*7 -4*(-7r) - (-4)*8 = 28
-3r + 21 + 28r + 32 = 28 {bring like terms together}
-3r + 28r + 21 + 32 = 28
25r + 53 = 28
25r = 28 - 53
25r = - 15
r = -15/25
r =-3/5
