Suppose the demand curve representing phone calls

Suppose the demand curve representing phone calls placed by Michconsin Electronics (ME) remains unchanged over time and is linear. ME currently uses MCI for phone calls and places 100 calls per month at a price of $0.80 per phone call. ME used to subscribe to AT&T and placed 90 calls per month at a price of $.90 per phone call, but switched to MCI to take advantage of the lower price. To lure customers like ME, AT&T recently modified its pricing structure to the following: $1.00 per call for the first 60 calls, $.80 per call for the next 40 calls, and $.50 per call for all remaining calls. Calculate the change in consumer surplus for ME if ME switches back to AT&T.