Explanation:
1) 3 - 4
Solving wih an equivalent addition problem:
Change the subtraction to addition. Subtracting 4 is the same as adding -4
3 + (-4) = -1
2) -3 - 4
Change the subtraction to addition. Subtracting 4 is the same as adding -4
-3 + (-4) = -7
3) -3 - (-4)
Change the subtraction to addition. Subtracting -4 is the same as adding +4
-3 + 4 = 1
4) 3 - (-4)
Change the subtraction to addition. Subtracting -4 is the same as adding +4
3 + 4 = 7
