Question

5(3m-4)=-15

Answer 1

5(3m-4)=-15
3m-4=-5
3m=-1
m=-1/3

Answer 2

Your second step should read:
\[3m-4=-3\]
This would change the following steps.
\[3m=1\]
\[m=\frac{1}{3}\]

Answer 3

5(3m-4)=-15
15m -20=-15
15m = -15+20
15m= 5
m= 5/15
m=1/3