Let x equal the number of tiny book boxes and y equal the number of large book boxes.
Because John must pack at least 35 boxes:
(number of tiny book boxes) + (number of large book boxes) = (at least) 35
x + y ≥ 35
Since John needs to pack at least 350 books:
(number of small books packed) + (number of large books packed) (is at least) 350
(number of small books per box)(number of boxes of small books) + (number of large books per box)(number of boxes of small books) ≥ 350
15x + 8y ≥ 350
Your system of inequalities is:
x + y ≥ 35
15x + 8y ≥ 350
GO INTO DESMOS TO GRAPH