A property of rectangles is that opposite sides are congruent. In this case, since QT and RS are opposite sides, they are equal to each other. With this knowledge, you can form the equation [tex] 50=4x+8 [/tex] to solve for x.
Firstly, subtract both sides by 8: [tex] 42=4x [/tex]
Next, divide both sides by 4 and your answer will be [tex] 10.5=x [/tex], or the third option.
