What system of equations could I use to solve this simple story problem?

King Street Printing recently charged 1.9 cents per sheet of paper, but 2.4 cents per sheet for paper made of recycled fibers. Darren's bill for 150 sheets of paper was $3.41. How many sheets of each type were used? If you guys know of the correct system, i should be able to take it from there. I cannot seem to figure out what it is supposed to be.