Quantities of water cement, sand and gravel in concrete

[Ali_003]

Please can someone help me with how to solve this question?
A 1:2:4 concrete mix is to be designed. Assume w/c ratio of 0.55, aggregate to cement ratio of 5.2 and a combined aggregate specific gravity of 2.7. Take the specific gravity of cement as 3.15. Calculate the mass of cement, coarse and fine aggregates and water that will fill a section of 250 x 210 x 120 cm