# How do you evaluate x+2y given x=1/2 and y=-2/5?

Nov 8, 2016

$- \frac{3}{10}$

#### Explanation:

Substitute the given numeric values for x and y into the expression.

$\Rightarrow x + 2 y = \frac{1}{2} + \left(2 \times - \frac{2}{5}\right)$

$= \frac{1}{2} + \left(- \frac{4}{5}\right) = \frac{1}{2} - \frac{4}{5}$

Before subtracting the fractions, we require them to have a common denominator.

$\Rightarrow \left(\frac{1}{2} \times \frac{5}{5}\right) - \left(\frac{4}{5} \times \frac{2}{2}\right) = \frac{5}{10} - \frac{8}{10} = - \frac{3}{10}$