Mrs. ernat needs to make two pies for . each pie bakes at 400 degrees f. the cherry pie bakes for 1 hour, and the pumpkin pie bakes for 50 minutes. mrs. ernat would like the pies done at the same time. her guests are coming at 11 am. however she doesn't need the pies until 1 pm. if it takes her 10 minutes to preheat, at what time should she turn the oven on, and put each pie in the preheated oven?

show and explain your work in the "what i did, and why i did it" format.