Answer:
The length of the container is

Explanation:
we know that
The surface area of a triangular prism (a mailing container) is equal to

where
B is the area of the triangular base
P is the perimeter of the triangular base
L is the length of the container
step 1
Find the area of the base B

step 2
Find the perimeter of the base P

step 3
Find the length L of the container
we have



substitute and solve for L

![L=[87.4-2(1.7)]/(6)](https://img.qammunity.org/2020/formulas/mathematics/high-school/h95f2qyibbz8c0zit14axozh6krrs5iv60.png)
