Pre Algebra Review

• The inverse operation of ADDITION is SUBTRACTION

• The inverse operation of MUTIPLICATION is DIVISION

• When adding the same sign, add and keep the sign.

• When adding different signs, find the difference of both numbers and take the sign of the number you have more of.

I have an addition sign (that's good).  My numbers have two different signs, so I have to find the difference of 12 and 27.  It is 15.  Now, I have more positives (27) than negatives (-12).  So, my answer is positive.  Answer is 15.

• Do "keep, add, opposite".

• Keep the first number, change minus sign to plus sign, and take the opposite of the second number.

• Use your addition rules.
  

Do "keep, add, opposite".  Keep the (-17), change the minus to a plus, and change the 6 to a (-6).  Now, we have (-17) + (-6).  Use addition rules.  We are adding the same sign, so add and keep the negative.  Answer is (-23).

• Same Signs= Positive Answer
• Different Signs= Negative Answer