Stack it and line things up in stripes:

Start with the ones...  See if you can do the subtraction:
 

Remember how to fix it?

We borrow (regroup) from the tens stripe.  I'm going to do it on the next page...  See if you can figure it out on your own before looking!  Split the 7 into a 6 and a 1...

Go to the next page for the rest!