Perform the Indicated Operations $\frac{7 a+9 b}{2}-\frac{7 a-9 b}{2}$ A) $81 \mathrm{~b}$

Multiple Choice

Perform the indicated operations. Give the answer in lowest terms.
- $\frac{7 a+9 b}{2}-\frac{7 a-9 b}{2}$

A) $81 \mathrm{~b}$
B) $9 b$
C) $7 \mathrm{a}$
D) 0