Greg needs to practice 18 more minutes today for playing clarinet.
A percentage is a number or ratio that can be expressed as a fraction of 100. Percentage can be calculated by dividing the value by the total value, and then multiplying the result by 100.
For the given situation,
Greg practiced playing his clarinet for 12 minutes.
He has practiced 40% of the amount of time he needs to practiced today.
Let x be the total time Greg needs to practice, that is 100%.
⇒ [tex]40\%=12[/tex]
⇒ [tex]100\%=x[/tex]
⇒ [tex]x=\frac{(12)(100)}{40}[/tex]
⇒ [tex]x=30[/tex]
Total amount of time Greg needs to practice is 30 minutes.
Thus, amount of time Greg need to practice today is
⇒ [tex]30-12[/tex]
⇒ [tex]18[/tex]
Hence we can conclude that Greg needs to practice 18 more minutes today for playing clarinet.
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