You can know the n-factor.
1st case:- n-factor=5 [Mn(7) to Mn(2)]
Now, this is one of the best concepts of mole concept,
"The EQUIVALENTS(normality×volume) of all reactants and products are EQUAL."
Do the same in the next case but n-factor in 2nd case is 3.
Solve it further by yourself, it will help you to gain confidence.