Percents you mean yield?
Ok, so to get 1 mole of product 3 you need 1 mole of reagent 1 and 2 moles of reagent 2. So from 370grams of 2 (2 moles) of you get, theoreticaly, 255 grams of 3 (1mole). If you use lesser amount of reagents you get lesser amount of product.
When you do your reaction you only get lets say 150 grams of 3 that is 150/255=0,588 -> 58% yield.
Equivalent means same molar amount of reagent. So if its 2 eq its twice that much.
I hope I answered your question and calculated molecular weights correctly