Ok guys, here's what i get from a similar example.
Given 12.6g of 2HNO3 and 15g of CaCO3, how much CaCO3 is left after the reaction is over.
2 moles of 2HNO3=126.02g and 1 mole of CaCO3 = 100.1g
100.1 : 164.1 = 15g : x
x = (100.1 / 126.02) x 12.6g = 10g of CaCO3 left over???