The lateral area of the prism is the area of the three rectangles in the middle of the net. (The two triangles are the bases of the prism, which don't count toward lateral area.) The total length of the three rectangular prism faces is (8 +15 +17) cm = 40 cm. The width of those rectangles is 11 cm. The lateral area will be the product of this length and width:
... lateral area = (40 cm)(11 cm) = 440 cm²