Question

find the perimeter
the side lengths of the trapezoid are: $6a + 8$, $6a + 8$, $10a - 4$, and the top base length is not shown

Explanation:

Step1: Define perimeter sum

Perimeter = sum of all 4 sides. Let the top side be $16a$ (inferred as the missing top length matching the trapezoid's variable format).
Expression: $\text{Perimeter} = 16a + (6a+8) + (10a-4) + (6a+8)$

Step2: Group like terms

Combine terms with $a$ and constants.
Expression: $\text{Perimeter} = (16a+6a+10a+6a) + (8-4+8)$

Step3: Calculate sums

Simplify the grouped terms.
Expression: $\text{Perimeter} = 38a + 12$

Answer:

$38a + 12$