First, look at the x axis (this is the one labeled Minutes Used per month)
Find the number 40, then look at where the lines meet on that line. The red line for Plan B it’s at 8 dollars. The blue line for Plan A is at 4 dollars.
Plan B costs more.
To find the difference, subtract 4 from 8.
$8 - $4 = $4
Plan B costs 4 dollars more than Plan A.
If you have any further questions feel free to ask.