Question

the perimeter of a trapezoid is 39a-7. Three sides have the following lengths: 9a, 5a-1, and 17a-6. What is the length of the fourth side

Answer 1

Since there are 4 sides, the total minus the 3 other sides gives you the 4th side. 39a-7-9a is 30a-7, 30a-7-(5a-1)=30a-7-5a+1 (using the distributive property) =25a-6, 25a-6-(17a-6)=8a