What is the chemical equation for: hot iron reacts with hot steam to form iron(II,III) oxide and hydrogen gas is released?

Iron(II,III) oxide has the formula  `Fe_3O_4,` and water steam has the same formula as water, `H_2O.` Therefore the unbalanced equation has the form

`Fe + H_2O =Fe_3O_4 + H_2.`

To balance this equation, first look at  `Fe:` one at the left and `3` at the right. So give `Fe` at the left the coefficient `3.` It becomes

`3Fe + H_2O = Fe_3O_4 + H_2.`

Then count oxygen `O:` `1` at the left side and `4` at the right side. Thus give `H_2O` at the left the coefficient `4:`

`3Fe + 4H_2O = Fe_3O_4 + H_2.`

And finally take into account hydrogen `H:` `8` at the left, `2` at the right. So it is enough to give the coefficient `4` to `H_2:`

`3Fe + 4H_2O = Fe_3O_4 + 4H_2.`

Now the equation is balanced.