Any one know how to do this my son need help

B) Profit per shirt goes from $10 to $15

Explanation:

Focus on the two points (2,0) and (3,10). The slope of the line through these points is

m = (y2-y1)/(x2-x1)

m = (10-0)/(3-2)

m = 10

Meaning the profit per shirt for this line is $10 per shirt.

Now move onto the other line. Focus on the points (9,40) and (11,70)

m = (y2-y1)/(x2-x1)

m = (70-40)/(11-9)

m = 15

The profit per shirt has gone up to $15 per shirt

m a t h w a y. c o m

step-by-step explanation:

$12. that is my answer.