If Trevor spends $20 more than Reed every year to buy toys, Reed spends $80-$20 =$60.
Since Reed uses $60 every year to buy toys, his friend Quinn uses 60/2 = $<<60/2=30>>30 every year to buy toys.
The total amount of money the three spend in a year together to buy toys is $30+$60+$80 = $<<30+60+80=170>>170.
The total amount of money the three will use to buy toys in 4 years is $170*4 = $<<170*4=680>>680.
#### 680