Brett has a snow-cone stand outside the local roller-skating rink. He has noticed that his sales tend to increase as the temperature rises. He collected the data below over the last 12 weeks.

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!