Andy blew up 50 balloons – the 12 balloons Ashley blew up = <<50-12=38>>38 balloons.
We know how long it took Andy to blow up 2 balloons, so 38 balloons / 2 = <<38/2=19>>19 time increments.
We know the time increment is 5 minutes, so 19 x 5 minutes = <<19*5=95>>95 minutes.
#### 95