Answer:
$60
Step-by-step explanation:
Producer surplus is defined as the difference between the price that a producer is willing to charge for its products or services, and their actual selling price.
let S = supplier surplus
(S - $15) + (S - $25) + (S - $40) = $100
3S - $80 = $100
3S = $180
S = $180 / 3 = $60