Answer:
- large: 40 lbs
- small: 20 lbs
Step-by-step explanation:
A system of equations can be written for the weights of the boxes based on the relationships given in the problem statement. One equation will be for the total weight of 1 large and 1 small box; the other will be for the total weight of 70 large and 60 small boxes.
Let L and S represent the weights of Large and Small boxes, respectively. The system of equations is ...
L + S = 60 . . . . . . combined weight is 60 lbs
70L +60S = 4000 . . . . weight of boxes in the truck
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We can solve this by substituting for s in the second equation.
70L +60(60 -L) = 4000
10L = 400 . . . . . . . . . subtract 3600, simplify
L = 40
S = 60 -L = 20
A large box weighs 40 pounds; a small box weighs 20 pounds.
