1st find the z. Well 4z+3 is on both sites so 8z+6 and 5z+1 times 2 is 10z+2 add them and you get 12z+8=224 Now take away 8 from both sides to make it 216 and divide both sides by 12 and you get 18. Now just plug in the variable so 4x18+3 which is 75. And if it is a rectangle then it will be the same on both ends.