You could have the item name in x,0, the amount in x,1 and the weight in x,2, and the combined weight in x,3. Drop in the for loop so it comes out as set value at loopindex,3 to loopindex,1*loopindex,2.
Now all the total weight you're carrying is in y=4 for every item. You would now just total everything in y=4 as the total weight and compare it to the allowed weight limit.
Made an example here: https://www.dropbox.com/s/dm0rs5ryi8rtb ... .capx?dl=0