I think it might be r= -3
Answer:
r=-3
Step-by-step explanation:
-78=5r+3(5r-6)
Multiply 3 by 5r and -6
-78=5r+15r-18
Combine like terms
-78=20r-18
Add 18 to both sides (-78+18=-60. -18 cancels out.)
-60=20r
Divide 20 to both sides.
-3=r
