we know that
density=mass/volume--------> volume=mass/density
step 1
find the volume of water
mass=700 kg
density of water=1000 kg/m³
volume of water=mass/density-----> 700/1000----> 0.70 m³
step 2
find the volume of ice
mass=450 kg
density of ice=916 kg/m³
volume of ice=mass/density-----> 450/916----> 0.49 m³
volume of water is 0.70³
volume of ice is 0.49 m³
volume of the mixture is (0.70+0.49)-----> 1.19 m³
the answer is
the volume of water is 0.70 m³