First you will want to convert the molarity of each to moles. To do this multiply the molarity by the volume in liters. Next add the moles together and divide that by the total volume of the solution. Molarity = moles/liters Solution First you will want to convert the molarity of each to moles. To do this multiply the molarity by the volume in liters. Next add the moles together and divide that by the total volume of the solution. Molarity = moles/liters.