Answer:
b = 4
Step-by-step explanation:
-15b + 21 + 5b =-19
Combine like terms
-15b +5b +21 = -19
-10b +21 = -19
Subtract 21 from each side
-10b +21 -21 = -19-21
-10b = -40
Divide each side by -10
-10b/-10 = -40/-10