<u>Final Answer:</u>
x = 20
<u>Step-by-step explanation:</u>
we'll be using the pythagorean theorem method, in this triangle the missing letter is a.
formula: 
a = x
b = 21
c = 29
a = 
a =
(note: 29² = 29 × 29 = 841 and 21² = 21 × 21 = 441)
a = 
a = 20
x = 20
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?
1 person make 3 cakes.
40 people make 40 x 3 = 120 cakes.
15% were chocolate = 15% x 120 = 0.15 x 120 = 18
Answer: There were 18 chocolate cakes made for bake sale.