Answers

2015-09-01T15:32:21+08:00
In adding integers, we must remember this steps.
First, you must keep the first number.
The first number is -15, so keep it.
We now have:
-15
Second, you must flip the sign, addition sign will be subtraction sign and vice versa.
The sign is +, so we must make it - . 
We now have
-15 -
Third, you must change the sign of the second number, positive becomes negative and vice versa.
The second number is +20, so it is positive, we'll change it to negative, so it becomes -20.
We finally have
-15 - (-20)
Lastly, we must do the operation based on the sign. Apply common sense. 
-15 - (-20)
it is like you are paying the money you borrowed, which is 15, and you pay 20. Now your change is going to be five. 
-15 - (20) = +5 or simply 5


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2015-09-01T20:10:26+08:00
5 is the answer.
Because in adding integers we should add it normally if it is a like sign. For example.....
+20 (+) +35= +55 or 55
-60 (+) -54= -114
And in adding unlike signs we should just subtract it. Then copy the sign of largest number. For example............
-38 (+) +10= -28
-60 (+) +97= +37 or 37
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