... iron deficiency in a child aged 12? Thx

A 12 years weighted 32kg's child is suffering from Iron Deficiency: hemoglobin level is 7.5 and RBC's count is low "3.7". I have a box of Ferrous Sulfate tablet "325 Mg" from "Nature Made". The question is what is the ideal dose for the child and can I use the 325mg tab in this case.
Thx