Question 45029
Here is a basic review of adding and subtraction numbers:
1). The absolute value of a number is the distance away from zero on the number line. For example the absolute value of 2 is 2 and the absolute value of -2 is also 2. Both are two spaces away from zero on the number line so their absolute value is 2.
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2). To add two numbers with the same sign, add the absolute values of both numbers and take the common sign: 
Example: -3 + -3 = absolute value of -3 + absolute value of -3 = 6.  The signs are the same so  -3 + -3 = -6
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3). To add two numbers with different signs, subtract the absolute values and take the sign of the larger number.
Example: -5 + 2 = absolute value of -5 minus absolute value 2 = 3.  The signs are different, 5 is the largest and has a negative sign, so = -5 + (+2)= -3
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4). To subtract any two numbers, change the subtraction sign to addition. Change the sign of the second number to the opposite sign. Apply the rules of addition. 
Example: 5-2 =  5 – (+2) Expanded version of the same problem.
5+(-2) Change to an addition problem.  Change the sign of the second number. 
5+ (-2) = 3  Apply the addition rules for when the signs are different.
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-3 + (-4) + (+12) Since the only operations are addition and subtraction work from left to right.
-3 +(-4)Signs are the same, so add.
-7+(+12) = 5 Signs are different, so subtract and take the sign of the larger number