#### Answer

$\frac{13}{36}$

#### Work Step by Step

In order to add or subtract fractions, we start by making a common denominator (bottom of the fraction). Thus, we multiply 7/9 by 4/4 and 5/12 by 3/3 (this is legal because 4/4 and 3/3 equal one) to obtain:
$\frac{28}{36}$+(-$\frac{15}{36}$)=$\frac{13}{36}$
(Recall, adding a negative is the same as subtraction.)