You create two equations as you want the left hand side (LHS) to equal 0 (RHS), thus if one of the brackets becomes 0 it will result in the whole LHS beocming 0 as the brackets are being multiplied (anything multiplied by 0 = 0)
Use formula p=m/v P is density M is mass V volume So you have the volume already now 8x5x4= 160 which is the volume P= 1800/160 after you divide you get 11.25 The density is 11.25
