Set up a system to find a and g.

Question

In the textbook office is a box of new math books, some for Geometry and some for Algebra 2. A label on the box reads: "Contents: 15 books, Weight: 61 lbs." You know that Geometry books weigh 3 pounds each, and Algebra 2 books weigh 5 pounds each. Let g = the number of Geometry books in the box, and a = the number of Algebra 2 books in the box.

Answer 1

a+g=15

5a+3g=61

a=15-g

5(15-g)+3g=61

75-5g+3g=61

75-2g=61

75-61=2g

14=2g

g=7 geometry books

a=15-7

a=8 algebra books