Four shelves were used. Three shelves had exactly 7 cars. The fourth shelf contained had 8.
If my ans was helpful u can follow me.
So first divide 420 by 3 which gets you 140 so now you need to divide that 140 by 20 which is 7 so the jeweler could make 7 necklaces which is B. If you have any questions just ask. Hope I helped you ❤️
Hello! The two pieces are 15 inches and 21 inches
