However much the barber charges.

First see what 4 could go by and the answer closest to 18 that is not more than the answer is the first number of the answer.
4×1=4
4×2=8
4×3=12
4×4=16
In this case 4 is the first number of the answer because if you fo 4 by 5 it equals 20 , which is more than the answer
4×5=20
after that , you subtract the answer, 18 minus 16 which is 2 because nothing times 4 equals 2
So the remainder is 2/4 or .50
If you have any questions about this please don't hesitate to ask me
I think it’s the red line.
So you want to put the equation into y=mx+b so you would need to subtract the x to put it on the right side so then you’ll have 2y=-x+0 then divide by 2 to get the y by itself then you’ll have y=-2x+0 that means the line would be negative and the y intercept is 0 and the only line that follows that is the red line.
Hope this helped :)