Subtracting (or “taking-away”) may seem hard at first, but it’s easy once you know how to do it.
First, you write the sum in a column like this:
In this case, the sum is 31 – 17. The first subtraction you need to do is 1 – 7. This is impossible without giving a negative number. So, we have to “borrow” one from the number on the top-left, like this:
So now the first sum we have to do is 11 – 7, which is 4.
The next thing we have to do is 2 – 1, which is 1.
We now know that our total answer to 31 – 17 is 14.