<human>:  Christopher uses 1 packet of a sugar substitute in his coffee. He has 2 coffees a day. The packets come 30 to a box and cost $4.00 a box. How much will it cost him to have enough sugar substitutes to last him 90 days?
<bot>: How many packets does Christopher use? ** He uses 1 packet per cup of coffee and he has 2 cups a day so that's 1*2 = <<1*2=2>>2 packets
How many packets does Christopher need? ** He wants enough to last him 90 days and he uses 2 packets a day so that's 90*2 = <<90*2=180>>180 packets
How many boxes of sugar substitute does Christopher need? ** The packets come 30 to a box and he needs 180 packets so that's 180/30 = <<180/30=6>>6 boxes of sugar substitute
How much does each box cost? ** Each box costs $4.00 and he needs 6 boxes so that's 4*6 = $<<4*6=24.00>>24.00
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