## Algebra 1: Common Core (15th Edition)

We begin by following the instructions to plug -4 in for a and 7 in for b. Thus, we obtain: $-7-(-4)$ A key rule to remember is that subtracting a negative is the same as addition. Thus, it follows: $-7-(-4)=-7+4$ We must recall that a negative becomes more positive when a positive number is added to it. Therefore, we find: $-7+4=-3$