Gain inequality

y=5x+ 1 ①

6(x-2)≤y & lt； 6(x- 1) ②

Substitute ① into ② to get.

6(x-2)≤5x+ 1 & lt； 6(x- 1)

6x- 12≤5x+ 1 & lt； 6x-6

7 & ltx & lt 13

Then x = 8,9, 10, 1 1, 12.

Y = 4 1, 46,51,56,61respectively.

There are six groups of solutions.

So there are at least 8 boxes of 4 1 parts.