-78=-9(b+8)+4(b-9)

Solution for -78=-9(b+8)+4(b-9) equation:

-78=-9(b+8)+4(b-9)

We simplify the equation to the form, which is simple to understand 
-78=-9(b+8)+4(b-9)

Reorder the terms in parentheses
-78=+(-9b-72)+4*(b-9)

Remove unnecessary parentheses
-78=-9b-72+4+*(+b-9+)

Reorder the terms in parentheses
-78=-9b-72+(+4b-36)

Remove unnecessary parentheses
-78=-9b-72+4b-36

We move all terms containing b to the left and all other terms to the right. 
+9b-4b=-72-36+78

We simplify left and right side of the equation. 
+5b=-30

We divide both sides of the equation by 5 to get b. 
b=-6