Answer:
0 boxes minimum
Explanation:
The mass of the truck and paper must satisfy ...
22.5b + 2948.35 ≤ 4700 . . . . total truck mass cannot exceed bridge limits
22.5b ≤ 1751.65
b ≤ 77.85
The driver can take a minimum of 0 boxes and a maximum of 77 boxes of paper over the bridge.
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The question asks for the minimum. We usually expect such a question to ask for the maximum.