Answer:
Agency C offers the least expensive overall fee
Step-by-step explanation:
Alone from gross salary, you would make 24000 a year.
Agency A
24000 - ( 2000 x 0.5)
= 23,000
$1000 fee
Agency B
24000 - ( 2000 x 0.1 ) x 6
= 24000 - 200 x 6
= 24000 - 1200
= 22,800
$1200 fee
Agency C
24000 - (500 + 100)
= 24000 - 600
= 23,400
$600 fee
Another way to solve this is to use the Midpoint Formula. The midpoint of a segment joining points

and

is

So the midpoint of your segment is

Perhaps it helps to see that the x-coordinate of the midpoint is just the average of the x-coordinates of the points. Ditto for the y-coordinate of the midpoint; just average the y's.