The graph shows the number of hours that Tammy spends typing for work, x, and the amount of pay that she earns, y. A graph titled Tammy's Pay with number of hours on the x-axis and pay in dollars on the y-axis. A line goes through points (2, 18) and (8, 42).

What does the y-intercept represent?
tammy initially $10 pay
tammy will type for 10 minutes each day
tammy initially had $4 pay
tammy will type 4 minutes each day