Question 913024
Perimeter of triangle = (x+6) + (x+3) + (x+9) = 3x + 18
Perimeter of rectangle = 2((x+1) + (x+4)) = 2(2x+5) = 4x + 10


These two are equal, so 3x + 18 = 4x + 10 --> x = 8.