Subtracting large numbers (especially with millions) such as billions, millions, thousands, etc. can be difficult especially if you are JUST learning about it.
You should just remember basic subtraction skills and use that for each individual digit.
If you run into a number that cannot ever mathematically be subtracted (unless you count -negative numbers), all you do is add a 1 next to that number and take -1 from the number to the left of it.
94,175,695 - 23,388,328 ---------------------
Take the 5 - 8 and make it a 15. Take -1 from the 9 beside it. 15-8=7. 8-2=6. 6-3=3. So far we have 763. Keep on doing this.
5 - 8 is mathematically impossible, so make it a 15 (once again!) and take -1 from the 7 beside it. 15-8=7, etc.
The answer is 70,787,367.
I hope I helped!