Let N be the number of 55 lb boxes
Then 110 - N = the number of 30 lb boxes
So we have that
55N + 30 (110 - N) = 4800 simplify
55N + 3300 - 30N = 4800
25N + 3300 = 4800 subtract 3300 from both sides
25N = 1500 divide both sides by 25
N = 60 = number of 55 lb boxes
110 - N = 110 - 60 = 50 = number of 30 lb boxes
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