Allie solves the subtration problem 304-9 as follows

2 14
304
_ 9
_____
205

Explain to Allie what is wrong with her method, and explain why the correct method makes sense.

Thank you

2 9 1
3 0 4
- 9
2 9 5


You can't take anything away from the zero, so you have to cross out the 3, write in 2, then you have 10, cross that 10 out and you write 9 and then you have 14 from which you take away 9 and carry the rest down, does that make sense?