Question

the perimeter of a pentagon is 20t+7. four sides have the following lengths: 6t, 2t, 4t-5, and 5t+1. what is the length of the 5th side?

Explanation:

Step1: Sum the 4 known sides

$(6t) + (2t) + (4t-5) + (5t+1)$
$=6t+2t+4t+5t -5+1$
$=17t -4$

Step2: Subtract sum from perimeter

Let the 5th side be $L$.
$L = (20t+7) - (17t-4)$
$=20t+7-17t+4$
$=3t+11$

Answer:

$3t+11$