The sandbox is 40 cubic feet because 2 x 4 x 5 = <<2*4*5=40>>40
He needs 120 pounds of sand because 40 x 3 = <<40*3=120>>120
He will take 60 trips because 120 / 2 = <<120/2=60>>60
He will need to drink water 15 times because 60 / 4 = <<60/4=15>>15
He will drink 45 ounces of water because 15 x 3 = <<15*3=45>>45
He will need 3 bottles of water because 45 / 15 = <<45/15=3>>3
He will spend $6 on water because 3 x 2 = <<3*2=6>>6
He will have $4 in change because 10 - 6 = <<10-6=4>>4
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