Acompound contains 70.18 % oxygen by mass. what mass of this compound would be needed to obtain 48.45 grams of oxygen?

                     69.036 g of Compound is required to obtain 48.45 g of Oxygen.

Explanation:

                    Let us assume that the total mass of the compound is 100 g. So it means that this compound weighing 100 is composed 70.18 % of Oxygen or among 100 g of this compound 70.18 g is constituted by oxygen only. Hence, we can make a relation as that,

                      70.18 g O is present in  =  100 g of a Compound

So,

         48.45 g of O will be present in  =  X g of a Compound

Solving for X,

                        X  =  100 g × 48.45 g ÷ 70.18 g

                        X  =  69.036 g of Compound