Anybody can help me answer this calculation?

A ship from Thailand make 20 times of journey to Singapore in one month. After a several years the ship hull experience same sort of major corrosion. Calculate the corrosion rate of the ship hull in mpy if the ship travels everyday in 7 years and after 7 years, the ship hull loss 17.8 kg from its original weight. The area of ship hull, density and atomic weight is 2500 cm2, 7.87 g/cm3 and 55.85 g/mol respectively.