Chapter 8.1, Problem 30E

To determine

To evaluate:

The givenexpression, when $x=-5$ and $y=-7$ .

Answer to Problem 30E

The value of given expression would be $13$ .

Explanation of Solution

Given:

An expression: $3x-4y$

Calculation:

To find the value of the given expression, we will substitute $x=-5$ and $y=-7$ in our given expression as shown below:

  $\begin{array}{l}3x-4y\left(\text{Given expression}\right)\\ \Rightarrow 3(-5)-4(-7)\left(\text{Substituting given values}\right)\\ \Rightarrow -15-4(-7)\left(\text{Using property (}-)(+)=(-)\right)\\ \Rightarrow -15+28\left(\text{Using property (}-)(-)=(+)\right)\\ \Rightarrow 13\end{array}$

Therefore, the value of given expression would be $13$ .