A delivery truck is transporting boxes of two sizes: large and small. The large boxes weigh 45 pounds each, and the small boxes weigh 25 pounds each. There are 120 boxes in all. If the truck is carrying a total of 4300 pounds in boxes, how many of each type of box is it carrying?

50 (115-y) + 25y = 4125 [from eq2]

5750 - 50y + 25y = 4125 [distribute]

5750 - 25y = 4125

-25y = - 1625

y = 65 [divide both sides by (-25) ]

There are 65 small boxes.

Put that value into either equation (now, which is easier?) to solve for x:

x = 115 - y

x = 115 - 65

x = 50

There are 50 large boxes.

- Mring0506