Solve Simplify the Answer $1 \frac { 1 } { 8 }$

Multiple Choice

Solve. Simplify the answer.
-A laminated lab bench has $1 \frac { 1 } { 8 }$ inches of plywood, $1 \frac { 1 } { 5 }$ inches of pressed board, and $\frac { 1 } { 2 }$ of an inch of formica. What is the thickness of the lab bench?

A) $\frac { 21 } { 25 } \mathrm { in }$ .
B) $1 \frac { 4 } { 21 } \mathrm { in }$ .
C) $\frac { 40 } { 113 } \mathrm { in }$ .
D) $2 \frac { 33 } { 40 } \mathrm { in }$ .