Greg practice playing his clarinet for 12 minutes. He has practice 40% of the amount of time he needs to practice today. How many more minutes does Greg needs to practice today.

If 12 is 40%

What is 60%

First we need to find out how long he needs to practice with a proportion

12/x = 40/100 x=30 minutes

Next, we need to find out what is 60% of 30 with a proportion

x/30 = 60/100 x=18 minutes

Greg needs to practice for 18 more minutes

12x2 = 80%, 6=20%, 30minutes=100%