Question

find rs in rectangle qrst.
rs = \square

Explanation:

Step1: Set equal opposite sides

In a rectangle, opposite sides are congruent, so $QT = RS$.
$\boldsymbol{c - 18 = 3c - 78}$

Step2: Solve for $c$

Isolate $c$ by rearranging terms.
$78 - 18 = 3c - c$
$60 = 2c$
$c = \frac{60}{2} = 30$

Step3: Substitute $c$ into $RS$

Use $RS = 3c - 78$ and $c=30$.
$RS = 3(30) - 78$

Answer:

12