First, we determine the area of the rectangular house by multiplying the length by the width. That is,
area of the house = (50 ft)(24 ft) = 1200 ft²
Given that all sides of the house should have the pathway, the length of the house plus the pathway should be 50+2x and the new width would be 24+2x. The new area minus the original area of the house should not be more than 345 ft². Thus, the equation would be,
(50+2x)(24+2x) - 1200 ≤ 345