You are knitting a scarf for your best friend and want to have it finished by 6pm. You want the scarf to 60 inches long when it is complete. At 1pm you have already knit 15 inches of the scarf, and you estimate that from this point on, you can knit at the rate of 1/4 inch per minute.

1) Write an equation that represents the length of the scarf, in inches, in terms of the number of minutes.