The oxidation state of the compound Mn (ClO4)3 is to be determined in this problem.
For oxygen, the charge is 2-, the total considering its number of atoms is -24.
Mn has a charge of +3.
TO compute for Mn, we must achieve zero charge overall hence 3 + 3x - 24 = 0 where x is the Cl charge.
Cl charge, x is +7.