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.

Geomertry 
PsyDAG,
Substitute 4d for e in second equation and solve for d. Insert that value into the first equation and solve for e. Check by inserting both values into the second equation.
See your later post. 
Geomertry 
Henry,
The following areas are equal:
1. Front and Back.
2. Left and right.
3. Top and Bottom.
Therefore, we calculate 3 areas and
multiply each by 2 to get the 6 areas:
As=2(3*h) + 2(10*h) + 2(10*3)=1901n^2.
6h + 20h + 60 = 190,
26h = 190  60 = 130,
h = 5in.