This is how I solved The problem:
So there are 172 and 67
172 - 67
So you take away the 2 and the 7 from the hundred and the ten which makes 170 and 60
170 - 60= 110
You then do a take away in between which makes 110
Then you bring back the 7 and 2, you also put a takeaway in between the 7
7-2=5
Which makes 5
Then you do 110 take away 5
110-5=105
This means the answer is 105