math word problems

Question

A delivery truck is transporting boxes of two sizes: large and small. The combined weight of a large box and a small box is 70 pounds. The truck is transporting 70 large boxes and 65 small boxes. If the truck is carrying a total of 4750 pounds in boxes, how much does each type of box weigh?

Answer 1

Let L = weight of large box

Let s = weight of small box

 

L + s = 70

70L + 65s = 4750

 

This can be solved by substitution or elimination.

Let's use elimination.  Multiply 1st equation by -65

and add equations.

 

-65L - -65s = -4550

70L + 65s =    4750

--------------------------

5L = 200

L = 40 pounds for a large box

 

40 + s = 70

s = 30 pounds for small box