Answer:
The linear demand function for Frog & Friends Shower curtains is q = -60p + 4,100
Explanation: $5 each ===> 3,800 curtains per month
$10 each ===> 3,500 curtains per month.
===> slope of the demand line is (3800-3500)/(5-10) = 300/-5 = -60
===> demand function is q = -60p + c for some constant c.
Let 3,800 = -60*5 + c.
=3800 = -300 + c
===> c = 4,100.
Therefore the linear demand function for frog & friends curtains is q = -60p + 4,100