The Watson family has been planning a vacation to Europe for the past two years. Gratton Savings agrees to advance a loan of $7,200 to finance the trip provided the Watsons pay the loan back in 12 equal monthly installments. Gratton will charge an add-on loan rate of 6%. How much in interest will the Watsons pay under the add-on loan rate method? What is the amount of each required monthly payment? What is the effective loan rate in this case? What is the amount of each required monthly payment? What is the effective loan rate in this case