Beverly has a bag of marbles that weighs 30 grams. She knows that each marble weighs 1. 5 grams and the bag weighs 1. 5 grams. Which equation could she use to determine how many marbles are in the bag? select all that apply. (1. 5)x + 1. 5 = 30 30 – x = 2(1. 5) (1. 5)(30) = 1. 5x 1. 5 + x = 30 1. 5x = 30 – 1. 5.