Complete the equation that is related to the given equation. m – 18.2 = –58

M-18.2=-15
First, what you want to do is undo the subtraction in m-18.2. The opposite of subtraction is addition, so you add 18.2 on both sides.
18.2+18.2 cancels out and leaves m alone. -58+18.2 is -39.8. I got that by going with this rule in adding and subtracting negatives and positives: "Same signs= add Different signs= subtract." So, here they are different sings, so you subtract. So now your problem looks like -58-18.2. If you do 18.2-15, then u get 39.9. Your answer takes the greater number's sign, and since -58 is greater and is negative, then so is your answer. 
Our final answer would be: -39.8