-1/4b + 1/2 = 5/6
Find b

b = -4/3

Step-by-step explanation:

First, subtract the 1/2 over

-1/4b+1/2=5/6

5/6-1/2

To get a common denominator of 6, multipy 1/2 by 3

5/6-1/2(3)

5/6-3/6=2/6

-1/4b=2/6

Next, multiply by the reciprocal of -1/4, or -4

(-4)-1/4b=2/6(-4)

b=-4/3

the surface area is 124cm²

step-by-step explanation:

length: 4cm

width: 9cm

height:   2cm