Chapter 5.3, Problem 79E

Alternative methods for adding and subtracting two fractions are shown below. These methods may not result in a solution in its lowest terms.

$\frac{\text{a}}{\text{b}}\text{+}\frac{\text{c}}{\text{d}}=\frac{\text{ad + bc}}{\text{bd}}$ and $\frac{\text{a}}{\text{b}}-\frac{\text{c}}{\text{d}}=\frac{\text{ad}-\text{bc}}{\text{bd}}$

79. $\frac{5}{6}-\frac{7}{8}$