List all the numbers you have to add or subtract in a horizontal line. Place the sign of each number in front of that number, and then place the sign and the number into parentheses. An example is to display positive two as (+2) or negative four as (-4).
Add in addition or subtraction pluses and minuses between the parentheses to create the full math problem. For example (+2) + (-4).
Look at the consecutive signs next to one another in the problem. If two of the same sign are next to each other, the result will be addition. If the two consecutive signs are different, the result will be negative.
Cross out each set of consecutive signs and place the sign that matches the proper process underneath the crossed out signs. For example, if you have (+2)+(+4), then cross out the two '+' signs in front of the 4, and just put one '+' sign underneath them. If you have (+2)-(+4), then cross out the two opposite signs, and place one '-' sign underneath them.
Start at the beginning of the problem and add or subtract the two first numbers according to your new sign. Write this answer below the problem.
Calculate the next step of the problem by adding or subtracting the first answer with the next number according to the sign you placed below the problem. For example, if you have calculated (+2)+(+4) =+6 and the next number in the sequence is +(-7), you will use 6 - 7 to get your next answer.
Continue using the next answer in the sequence and adding it or subtracting it appropriately down the line until you finally get your final answer.