Answer
a. $x=\frac{C-60}{85}$
b. Number of ski trips for total cost of $\$315$ is $3$ and $485$ is $5$.
Work Step by Step
The given literal equation is
$\Rightarrow C=85x+60$
a.
$\Rightarrow C=85x+60$
Subtract $60$ from each side.
$\Rightarrow C-60=85x+60-60$
Simplify.
$\Rightarrow C-60=85x$
Divide each side by $85$.
$\Rightarrow \frac{C-60}{85}=\frac{85x}{85}$
Simplify.
$\Rightarrow \frac{C-60}{85}=x$ ...... (1)
b.
Substitute $315$ for $C$ in equation (1).
$\Rightarrow \frac{315-60}{85}=x$
Simplify.
$\Rightarrow \frac{255}{85}=x$
$\Rightarrow 3=x$
Substitute $485$ for $C$ in equation (1).
$\Rightarrow \frac{485-60}{85}=x$
Simplify.
$\Rightarrow \frac{425}{85}=x$
$\Rightarrow 5=x$
