Not sure if i understand but can someone help me understand by what its means of the problem?

Variable: b

Equation: $12b + $16 = $112

Solution: 8 books

Step-by-step explanation:

$12b + $16 = $112

$12b + $16 - $16 = $112 - $16

$12b = $96

$12b ÷ $12 = $96 ÷ $12

b = 8

Hope that helps.

then, the surface area of the sphere shown in the image is: 256π sq. units!

step-by-step explanation:

the lateral surface area of a sphere is 2πrh where h=2r.

then:

surface area = 4πr^2.

in this case, r=8 units ⇒ surface area = 4π(8 units)^2. = 256π sq. units!

then, the surface area of the sphere shown in the image is: 256π sq. units!