He now buys 4/2=<<4/2=2>>2 coffees
The new price is 2*.5=$<<2*.5=1>>1 more than the old price
So he now pays 2+1=$<<2+1=3>>3 per coffee
So he spends 3*2=$<<3*2=6>>6
He used to spend 4*2=$<<4*2=8>>8
So he saves 8-6=$<<8-6=2>>2 per day
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