X+y=75, 10x+y=48, list the y-coordinate

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

The graph of a curve that passes the vertical line test is a:

Can someone me find the original price? the discount is 5% and the sale price is $68.40