The correct answer is B. 7.5
Similar polygons are polygons wherein its corresponding sides are proportional. All corresponding sides of the larger polygon are proportional to the corresponding sides to the smaller polygon, wherein segment HG is proportional to segment DC, and segment FG is proportional to segment BC. (See attachment for reference) A proportion is an equation that states two ratios are equivalent. By cross multiplying the two ratios, you get an equation for finding the value of z, which is 7.5
