<human>:  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.
<bot>: How much laundry does Raymond do? ** 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.
How much laundry does David do? ** Sara also does 4 times as much laundry as David, meaning David does 400/4 = <<400/4=100>>100 pounds of laundry.
How much is the difference in the amount of laundry Raymond and David do? ** The difference in the amount of laundry Raymond and David do is 200-100 = <<200-100=100>>100 pounds
#### 100