5/9. 5/6 times 2/3 and then simplifying is how I did this.
Such a prism would have 2 14x7 faces, 2 7x28 faces, and 2 28x14 faces. Then, the surface area of the prism would be
2 * 14 * 7 + 2 * 7 * 28 + 2 * 28 * 14 = 1372
F = (5/9)c + 32
F - 32 = (5/9)c
9(F-32) = 5c
(9(F-32))/5 = c
Answer: 6 vans
Step-by-step explanation: one of the vans would only have 6 people