<human>:  In one of the building blocks at Oakland High there are 5 classes. Each class uses 2 whiteboards each and each whiteboard needs about 20ml of ink for a day's use. If ink costs 50 cents per ml, how much (in dollars) would it cost to use the boards for one day?
<bot>: How much does each ml of ink cost? ** Each ml of ink costs 50 cents so 20 ml costs 20*50 = <<20*50=1000>>1000 cents
How much does each class need? ** There are 2 whiteboards in each class so each class needs 2*1000 cents = <<2*1000=2000>>2000 cents
How much do all the classes need? ** There are five classes in the block so they all need 5*1*2000 cents = <<5*1*2000=10000>>10000 cents
How much does it cost in dollars? ** 100 cents make a dollar so 10000 cents make 10000/100 = $<<10000/100=100>>100
#### 100