A university bookstore recently sold a wirebound graph-paper notebook for $1.10, and a college-ruled notebook for $3.16. At the start of spring semester, a combination of 50 of these notebooks were sold for a total of $102.38. How many of each type were sold?

Let x, y be the number of  wirebound graph-paper notebooks, colege rule note books.,

x+y=50.

1.1x+3.16y=102.38.

1.1x+3.16*(50-x)=102.38.

1.1x+158-3.16x=102.38.

2.06x=55.62.

x=55.62/2.06

=27.

y=50-27

=23.