Greg practiced playing his clarinet for 12 minutes. He has practiced 40% of the amount of time he needs to practice today. How many more minutes does Greg need to practice today?
You set up a proportion so: 12/x and 40/100 Cross multiply so 12 times 100 = 1200 and 40 times x = 40x 1200 divided by 40 = 30 minutes total You know that he already know he spent 12 minutes doing it so 30 - 12 = 18 more minutes
