Add your bottoms in a cross pattern
When you add 4 to 25 you get 21 then subtract 11 and get 10 and then add 15 which is equal to 25 and then subtract 13.
the answer is 12
You have to use PEMDAS, by multiplying before you add. So when you multiply 5*6, you get 30 and add the remaining 27 to get 57.
Answer:
For each part, find how many numbers have the stated characteristic, then divide by 21.
e.g. multiples of 5:
these would be 10, 15, 20, 25, and 30
so prob (a multiple of 5 ) = 5/21
Do the others the same way
