Solve Simplify the Answer $\frac { 3 } { 4 }$

Solve. Simplify the answer.
-Erika spent $\frac { 3 } { 4 }$ of an hour on her computer visiting the history channel and the discovery channel websites. She spent $\frac { 1 } { 3 }$ of an hour at the history channel website. How many hours did she spend at the discovery channel website?

A) $\frac { 5 } { 12 } \mathrm { hr }$
B) $\frac { 1 } { 6 } \mathrm { hr }$
C) $\frac { 1 } { 3 } \mathrm { hr }$
D) $\frac { 2 } { 3 } \mathrm { hr }$