If Raymond does half as much laundry as Sarah, and Sarah does 4 times as much laundry as David, calculate the difference in the amount of laundry Raymond and David do if Sarah does 400 pounds of laundry.
If Sarah does 400 pounds of laundry, and Raymond does half as much laundry as Sarah, Raymond does 1/2*400 = 200 pounds of laundry.
Sara also does 4 times as much laundry as David, meaning David does 400/4 = <<400/4=100>>100 pounds of laundry.
The difference in the amount of laundry Raymond and David do is 200-100 = <<200-100=100>>100 pounds
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