Lila wrote an equation of the cost for printing brochures, where x represents the number of brochures and y represents the total cost. The total cost for 35 brochures is $41.45. The total cost for 65 brochures is $55.55.

Step 1: Write the ordered pairs mc017-1.jpg and mc017-2.jpg.

Step 2: Find the slope. mc017-3.jpg

Step 3: Find the y-intercept to write the equation in slope intercept form. mc017-4.jpg

Which explains the error that Lila made?
Lila made in error in Step 1 by reversing the ordered pairs.
Lila made an error in Step 2 by not using the slope formula.
Lila made an error in Step 3 when she did not use the x- and y-coordinates from the same ordered pair.