Answer:
b = -23/16
Step-by-step explanation:
The variable x can be eliminated from the system by multiplying the first equation by -2 and adding that to the second equation.
-2(-4b +x) +(8b +2x) = -2(7) +(-9)
16b = -23 . . . . . collect terms
b = -23/16 . . . . divide by the coefficient of b
The value of b is -23/16 = -1 7/16.