On a 5 day wilderness expedition you'll need to heat 5.0kg of water to the boiling point each day. The air temperature will average 25C.

On a 5 day wilderness expedition you'll need to heat 5.0kg of water to the boiling point each day. The air temperature will average 25°C. You have available canisters of compressed propane C3H8 fuel, which you'll burn to heat the water. Each canister has 75.g of propane in it. What is the minimum number of fuel canisters you must bring? 

The standard heat of formation of propane at 25°C is −103.85/kJmol