Answer:
- large: 18.5 kg
- small: 15.75 kg
Step-by-step explanation:
Let b and s represent the weights of the big and small boxes, respectively. Then the two delivered weights can be summarized as ...
5b +6s = 187
3b +2s = 87
We can eliminate the "s" variable by subtracting the first equation from 3 times the second:
3(3b +2s) -(5b +6s) = 3(87) -(187)
4b = 74 . . . . . collect terms
b = 18.5 . . . . . divide by 4
Using this value in the second equation, we find ...
3(18.5) +2s = 87
2s = 31.5 . . . . . . . . subtract 55.5
s = 15.75 . . . . . . . . divide by 2
The large box weighs 18.5 kg; the small box weighs 15.75 kg.