Answer:
C. 468mm²
Step-by-step explanation:
The formula for the surface area of rectangular prism is:

Let's break down our variables.
L = 12mm
W = 6mm
H = 7mm + 2mm = 9mm
Now we substitute our values in the formula:
Answer:

Step-by-step explanation:
Let:

We need to eliminate one of the variables, so let's use elimination method. First multiply (1) by 2

Now subtract (2) from 2*(1) in order to eliminate x:

Solving for y:
Multiplying both sides by -1

Finally, replacing the value of y in (1)

Solving for x:
add 41 to both sides:

Multiply both sides by 1/2:

Answer:
Step-by-step explanation:
I don"t really know the answer but i might have and explanation to help. Hollow everyday circular objects appear differently than drawn two-dimensional circles. Objects like pipes and hoses have two different diameters. The outside diameter measures the distance of a straight line from one point on the outside of the object, through its center, and to an opposite point on the outside. The internal diameter measures the inside of the object. Calculating the internal diameter depends on the outside diameter and the thickness of the outer circle.