Answer
True
Work Step by Step
If $x_{1} \lt x_{2}$, and $f$ is a decreasing function then it is true that $f(x_1) \gt f(x_2)$
Because the function is decreasing, increasing values of $x$ have decreasing values of $f(x)$
Since $x_1$ is lower than $x_2$ its relative $f$ value will be higher
