Each ml of ink costs 50 cents so 20 ml costs 20*50 = <<20*50=1000>>1000 cents

There are 2 whiteboards in each class so each class needs 2*1000 cents = <<2*1000=2000>>2000 cents

There are five classes in the block so they all need 5*1*2000 cents = <<5*1*2000=10000>>10000 cents

100 cents make a dollar so 10000 cents make 10000/100 = $<<10000/100=100>>100

# Answer

100
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
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?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
100
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?
train