Tom needs to lower a rope down 6 stories.   One story is 10 feet.  The only rope being sold is 20 feet long but you lose 25% when lashing them together.  How many pieces of rope will he need to buy?
How many feet does Tom need? ** He needs 10*6=<<10*6=60>>60 feet
How many feet does Tom lose? ** He loses 20*.25=<<20*.25=5>>5 feet each time
How many feet does Tom get from each piece? ** So he gets 20-5=<<20-5=15>>15 feet from each piece
How many pieces of rope does Tom need? ** That means he needs 60/15=<<60/15=4>>4 pieces of rope
#### 4