need explanation on answer: Cameron makes a quilt design using four congruent triangles as shown below. 4 connecting congruent triangles are shown. The bottom 2 triangles share the same base. The top 2 triangles also share the same base and sit on top of the bottom 2 triangles. The base length is 21 centimeters. The length of the bottom side of the triangle is 14 centimeters. The length of the right side of the triangle is 9 centimeters. What is the perimeter of the entire design?