You can practice addition and subtraction of negative and positive numbers with this applet. Change the numbers and the sign and look at the answer in the line.
[list=1][*][b] -4 + 5 = [/b][/*][*][b]-6 - 4 = [/b][/*][*][b]-5 + 7 = [/b][/*][*][b]-5 + 9 = [/b][/*][*][b]2 + (-5) = [/b][/*][*][b]-9 - (-4) = [/b][/*][*][b]4 - (-7) = [/b][/*][*][b]11 + (-14) = [/b][/*][/list]