The left-hand mice cost 120*.3=$<<120*.3=36>>36 more than right-handed ones
So they cost 120+36=$<<120+36=156>>156
So he makes 156*25=$<<156*25=3900>>3900 a day
The store is open 7-3=<<7-3=4>>4 days a week
So in a week, he makes 3900*4=$<<3900*4=15600>>15,600
#### 15600