Adelivery truck is transporting boxes of two sizes: large and small. the large boxes weigh 50 pounds each, and the small boxes weigh 20 pounds each. there are 120 boxes in all. if the truck is carrying a total of 4050 pounds in boxes, how many of each type of box is it carrying?

So this is how we are going to solve for the given problem above.
Given that x = number of large boxes
and 120-x = number of small boxes.
So here is the solution:
50x + (120-x)20 = 4050
50x + 2400 - 20x = 4050
30x + 2400 = 4050
30x = 4050 - 2400
30x = 1650 <<divide both sides by 30
x = 55.
Therefore, there are 55 large boxes
120 - x = small boxes
120 - 55 = 65 small boxes.
Hope this is the answer that you are looking for.
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The third one i'm pretty sure