He is wrong.
The 10 inch cube is bigger than the 5 inch cube by 5 cm in EACH DIRECTION.
So, the 10 inch cube should be twice as big in volume by a factor of 2*2*2
=8
Okay let's see.
5 cm cube volume = 5*5*5 = 125 cc
10 cm cube volume = 10 * 10 * 10 = 1,000 cc
1,000 / 125 = 8
The answer is 5.35, 275, 336, and 535
Length: 2w + 59
width: w
diagonal: (2w + 59) + 2 = 2w + 61
Length² + width² = diagonal²
(2w + 59)² + (w)² = (2w + 61)²
(4w² + 118w + 3481) + w² = 4w² + 122w + 3721
5w² + 118w + 3481 = 4w² + 122w + 3721
w² + 118w + 3481 = 122w + 3721
w² - 4w + 3481 = 3721
w² - 4w - 240 = 0
a = 1, b = -4, c = -240
w = ![[-(b) +/- \sqrt{(b)^{2} - 4(a)(c) }]/2(a)](https://tex.z-dn.net/?f=%5B-%28b%29%20%2B%2F-%20%5Csqrt%7B%28b%29%5E%7B2%7D%20%20-%204%28a%29%28c%29%20%7D%5D%2F2%28a%29)
= ![[-(-4) +/- \sqrt{(-4)^{2} - 4(1)(-240) }]/2(1)](https://tex.z-dn.net/?f=%5B-%28-4%29%20%2B%2F-%20%5Csqrt%7B%28-4%29%5E%7B2%7D%20%20-%204%281%29%28-240%29%20%7D%5D%2F2%281%29)
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since width cannot be negative, disregard 1 - 2√61
w = 1 + 2√61 ≈ 16.62
Length: 2w + 59 = 2(1 + 2√61) + 59 = 2 + 4√61 + 59 = 61 + 4√61 ≈ 92.24
Answer: width = 16.62 in, length = 92.24 in
I divided the two fractions & drew a model.

So we know that the bird seed will last 2.5 days.
Knowing this, we can go with:
B. Rectangle model divided into six equal sections, five sections are labeled five-sixths and two sections are labeled one-third, equaling two and one-half days.
Let me know if you find any problems with my answer.