If yesterday the number of buyers was half the number of buyers the day before, then yesterday there were 1/2*50 = <<1/2*50=25>>25 buyers.
Today has 40 more buyers than yesterday, so there were 40+25 = <<40+25=65>>65 buyers today.
The total number of buyers in the store for the three days will be 65+25+50 = <<65+25+50=140>>140 buyers
#### 140