The equation that you are looking for is y = -2x + 3
x = total amount of students in 8th Grade.
we know only one-thrid of the class went, so (1/3)x or x/3 went.
we also know 5 coaches went too, and that the total amount of that is 41.

now, to verify, well, what do you get for (108/3) + 5?
Answer: 6 ounces
Explaintion: 24 minus 18 equals 6
3x + 22 is the equation that represents the perimeter of the triangle. 4x + 10 is the perimeter of the rectangle. Setting the two equal:

and collecting like terms:

We find that the perimeter of both shapes is equal to 11 units.