A university bookstore recently sold a wirebound graph-paper notebook for $2.15, and a college-ruled notebook for $3.43. At the start of spring semester, a combination of 50 of these notebooks were sold for a total of $134.38. How many of each type were sold?

Question

A university bookstore recently sold a wirebound graph-paper notebook for $2.15, and a college-ruled notebook for $3.43. At the start of spring semester, a combination of 50 of these notebooks were sold for a total of $134.38. How many of each type were sold?

Answer 1

G+C=50

G*2.15+C*3.43=134.38

multipy the first equation by -2.15
-G*2.15-C*2.15= -50*2.15
add it to the second equation.
G*0 +C*1.28 = 134.38-50*2.15

solve for C.
Then G=50-C