Finding Sum of Numerator and Denominator of a Rational Number

Let the rational number $x$ be defined as:

$$x = \f\frac{3}{4} - \f\frac{1}{2} + \f\frac{5}{6}$$

Given that this number can be expressed in the form $\f\frac{a}{b}$ where $a$ and $b$ are integers in their simplest form, what is the value of $a + b$?