56 would have a remainder of 2 using multiples of 3
56/3 = 18 remainder 2
56/6 = 9 remainder 2
56/9 = 6 remainder 2
56/18 = 3 remainder 2
56/27 = 2 remainder 2
Now divide 28 by the above numbers to see which ones have 1 as a remainder:
28/3 = 9 remainder 1
28/6 = 4 remainder 4
28/9 = 3 remainder 1
28/18 = 1 remainder 10
28/27 = 1 remainder 1
There are 3 numbers that will work.
Answer: c. 3
