Molly : she calculated 2 + 3 x 4.....and she got 20......so she basically added 2 + 3 (which equals 5), then multiplied by 4...giving her 20.
Nancy : she calculated 2 + 3 x 4...and she got 14...so she basically multiplied the 3 x 4 (which is 12) and added the 2.
Nancy is correct because in PEMDAS (the order of operations) multiplication comes before addition