A Formula Is Given, Along with Values for All but One

Multiple Choice

A formula is given, along with values for all but one of the variables in the formula. Find the value of the variable that is not given.
- $\mathrm{A}=\frac{1}{2} \mathrm{bh} ; \mathrm{b}=20, \mathrm{~h}=18$

A) $\mathrm{A}=38.5$
B) $\mathrm{A}=360$
C) $\mathrm{A}=38$
D) $\mathrm{A}=180.0$