Birch manufacturing is considering the addition of another product line to its offerings. Equipment needed to produce the new line will cost $191,400. Birch estimates that the net cash inflows from the new product line will be as follows:

Years 1-10 $18,620 (each year)

Years 11-15 $5,200 (each year)

Year 16-20 $2,190

(a) What is the payback period for the new product line? Payback period ___________________years