Chapter 6 - Systems of Equations and Inequalities - 6-3 Solving Systems Using Elimination - Practice and Problem-Solving Exercises - Page 379: 40

square area = 81 square centimeters triangle area = 15 square centimeters

s= square t = triangle $s+4t = 141$ $2s + 2t = 192$ $s+4t = 141$ $-2*(2s+2t=192)$ $s+4t = 141$ $-4s-4t = -384$ $s+4t-4s-4t = 141-384$ $-3s = -243$ $-3s/-3 = -243/-3$ $s=81$ $81+4t = 141$ $81+4t-81 = 141-81$ $4t=60$ $4t/4 = 60/4$ $t=15$