My teacher ask if 4-7 was 3 and i said yes and it wrong nooo
I assume your teacher explained WHY that answer was incorrect?
4 – 7 = –3 You had the "three" part right, but it's a negative three.
Think about if you had 4 dollars, and bought something that cost 7.
You wouldn't have 3 dollars left in your pocket, you would still owe 3.
In bookkeeping, they call that a negative balance.