Looking at this problem, you know that 3 - 7 will be B: 7 units to the left of 3. One way to know this is because you subtracted 7 from 3, meaning you took it away. When you take away, you go left on the number line, and you took away 7, so you went 7 left.
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7 + (-3)
When you add a negative number, it is the same as subtracting the number So, instead of +(-3), it will be just -3.
7 - 3 = 4
So your answer will be C: 4