Make the plans have the same cost at 18 months.
Plan A: y=0x + 10
Plan B: y = 0x

m=-2 b=0

Step-by-step explanation:

first, in order to understand anything, you gotta know what y=mx+b means :)

first, m is just there so you can substitute it for a number. x represents the slope, and b represents the y-intercept, which you also substitute for a number.

so in y= -2x, there's no y intercept, because there is no number that represents the y intercept.

so if we use y=mx+b, we can just substitute the numbers.

which would be, y= -2.