A hot pie that was cooked at a constant temperature of 325 F is taken

directly from an oven and placed outdoors in the shade to cool on a day

when the air temperature in the shade is 85 F. After 5 minutes in the

shade, the temperature of the pie had been reduced to 250 F.

Determine (a) the temperature of the pie after 20 minutes and (b) the

time required for the pie to reach 275 F.