Word problems with missing parts

Question

A paper company needs to ship paper to a large printing business. The paper will be shipped in small boxes and large boxes. The volume of each small box is 6 cubic feet and the volume of each large box is 13 cubic feet. A total of 19 boxes of paper were shipped with a combined volume of 156 cubic feet. Determine the number of small boxes shipped and the number of large boxes shipped.

Answer 1

b + s = 19

13b + 6s = 156

Can you solve the system and answer? I would use substitution.