You have just prepared a cup of coffee containing 250.0 g of coffee (assume its properties are the same as those of water) at 100 "C by heating it in the microwave oven. What mass of ice (at -20.00 *C) should you add to the coffee to cool it to a drinkable 60.00 C? (You may assume that the heat capacity of the cup is negligible and that no heat escapes to the surroundings.)