Answer
-97.8
Work Step by Step
To evaluate the expression, we substitute the values $x=-7.8$ and $y=8.4$ into the expression,
$5x-7y$
=$5(-7.8)-7(8.4)$
=$5(-\frac{78}{10})-7(\frac{84}{10})$
=$(-\frac{390}{10})-(\frac{588}{10})$
=$\frac{-390-588}{10}$
=$\frac{-978}{10}$
=$-97.8$
