Answer
$a = 6\frac{2}{3} $
Work Step by Step
$\frac{a}{20} + \frac{4}{15} = \frac{9}{15}$
Subtract $\frac{4}{15}$ from both sides.
Now you have $\frac{a}{20} = \frac{5}{15}$
Multiply each side by 20 to isolate $a$.
$a = 20( \frac{5}{15}) = \frac{100}{15}$
$a = 6\frac{10}{15} = 6\frac{2}{3} $
