Question

Eric earns a weekly salary and a commission on each item that he sells. The equation y = 10x + 50 represents the amount of money that Eric earns weekly. Bailey earns a greater weekly salary than Eric but the same commission rate. Which graph could represent the amount of money that Bailey earns weekly, y, based on the number of items sold, x?
A graph titled Bailey's Weekly Earnings has items sold on the x-axis and total earned on the y-axis. A line goes through points (0, 75), (5, 125), (10, 175).
A graph titled Bailey's Weekly Earnings has items sold on the x-axis and total earned on the y-axis. A line goes through points (0, 50), (1, 75), (2, 100).
A graph titled Bailey's Weekly Earnings has items sold on the x-axis and total earned on the y-axis. A line goes through points (0, 75), (1, 100), (2, 125).
A graph titled Bailey's Weekly Earnings has items sold on the x-axis and total earned on the y-axis. A line goes through points (0, 50), (5, 100), (10, 150).

Answer 1

Bailey must have the same slope 10 (same commission) and a larger y-intercept (>50). The first graph with points (0, 75), (5, 125), (10, 175) has slope (125−75)/5 = 10 and y-intercept 75, so it fits. (Equation: y = 10x + 75.)