Posted by Mary on .
The surface area of a rectangular prism is 190 square inches, the length is 10 inches, and the width 3 inches. Find the height.
I know how to do SA but I don't understand how to find height if you have SA given. The answer is 5 in but I am not able to come up with the right answer.

geometry 
PsyDAG,
Let x = height.
2(10*3) + 2(3x) + 2(10x) = 190
Solve for x.