A 100g piece of ice at 0 degrees celcius is placed into a container holding 200g of water, initially at temperature 25 degrees celcius. Heat flows from the water to the ice, cooling the water and melting the ice. Calculate

Question

A 100g piece of ice at 0 degrees celcius is placed into a container holding 200g of water, initially at temperature 25 degrees celcius. Heat flows from the water to the ice, cooling the water and melting the ice. Calculate 
a) how many moles of ice and how many moles of water are present
b) how much heat flows out of the water in cooling to 0 degrees celcius 
c) how many moles of ice are melted by this added heat

I am trying to find an equation to start this problem, but am having trouble doing so. I think that, once I determine the euqation(s), I should be able to solve the problem.