Since you have y=14 for both it’s easy! -214 is 214 blocks away from 0, 234 is 234 blocks from 0 since they are on positive and negative sides you have to add them 214+234= 448 units away
Because the weight for the bag of forgeries is one hundred grams more I think just by holding it you can know which one is the fake. To check you can grab each bag two at a time with outstretched arms using your balance to tell which one has a larger weight.