Question 60669
Well, a rectangular solid has six faces, opposite pairs of which are identical.

To find the volume of a rectangular solid, use the formula: 
{{{V = l*w*h}}} Where: l = the length, w = the width, and h = the height.

You are given the length: l = 10" and the width, w = 5"
If it is twice as wide as it is deep (same as height). 
So, 2h = w  and h = (1/2)w = (1/2)5 = 2.5

The volume is:
{{{V = (10)(5)(2.5)}}}
{{{V = 125}}}cu. ins.

To find the surface area of the six faces, find the areas of the three pairs of identical faces (2 sides, 2 ends, top & bottom).

One side: {{{A1 = l*h}}} = {{{(10)*(2.5) = 25}}} Multiply by 2 for both sides.
{{{2A1 = 2(25)}}} = {{{50}}} sq. ins.

For one end: {{{A2 = w*h}}} = {{{(5)*(2.5) = 12.5}}}  Multiply by 2 for both ends.
{{{2A2 = 2(12.5)}}} = {{{25}}} sq. ins.

For the top: {{{A3 = l*w}}} = {{{(10)(5) = 50}}}  Multiply by 2 for both top & bottom.
{{{2A3 = 2(50)}}} + {{{100}}} sq. ins.

Total surface area is: {{{2A1 + 2A2 + 2A3 = 50 + 25 + 100}}} = {{{175}}} sq. ins.