Answer
$\frac{3}{10}$
Work Step by Step
The opposite of a number $a$ is the number on the other side of the number line that is equal distance from 0 as $a$ is. We can find the opposite of a number by writing a negative sign in front of the number.
$-(-\frac{3}{10})=\frac{3}{10}$
Therefore, the opposite of $-\frac{3}{10}$ is $\frac{3}{10}$.
