Students in a summer art class paint a rectangular mural. The shorter side of the mural measures 5 yards. The longer side measures 3 yards longer than the shorter side. How many square yards is the mural's area?

Let's call the length of the longer side x yards.

Since the longer side is 3 yards longer than the shorter side, we can express the length of the longer side as x = 5 yards + 3 yards = 8 yards.

The area of a rectangle is calculated by multiplying the length by the width. In this case, the area of the mural is:

Area = Length x Width
Area = 5 yards x 8 yards
Area = 40 square yards

Therefore, the mural's area is 40 square yards.