An oven turned on at a room temperature of 20℃ and it takes 10 minutes to reach a temperature of 190℃. A cake is placed in the oven to bake for 30 minutes. The oven is then turned off and returns to room temperature after 15 minutes. The oven is turned on again 45 minutes later and it takes 15 minutes to reach a temperature of 160℃. Cookies are placed in the oven to bake for 20 minutes. The oven is then turned off and returned to room temperature after 15 minutes. Identify the dependent and independent variable in this scenario.