Question

3fe+H2O----Fe3O+4H2

how many grams of steam and iron mist reat to produce 375g of magnetic iron oxide

Answer 1

Here is a solved example of a stochiomtry problem. Just follow the steps to solve this one.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

...and note that you need to balance the starting equation, i.e. it is not balanced as written above.

Answer 3

i think that it is 3 grams of Googaw reat