Solution
By the Pythagorean theorem, 82 + 152 = (CE)2 (CE)2 = 64 + 225 = 289 CE = 17. Then the perimeter of CDE = 8 + 15 + 7 = 40. Triangles ABC and CDE are similar (each has a 900 angle, and the vertical angle at C are congruent). The ratio of similitude is = 2.5, so the perimeter of ABC is 2.5 × 40 = 100. The answer is (100).