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The highest temp was 136 deg F in Africa. The lowest was -129 deg F in Antarctica. How many degrees difference is there between these temps.?

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4 Answers

Consider first what they are asking for here.  Don't let the wording trick you up.  They are trying to find out how many degrees (or numbers) there are between the lowest on record and the highest on record. 
 
Think about this type of question like a number line.  Place zero in the middle, and your negative number (-129F) to the left of the zero, and your positive number (136F) to the right of the zero.  It should look like this:
 
-129---------------------------------------------0----------------------------------------------------------136
 
How many actual numbers are there when you count from 0 to -129?  129, right?  It doesn't matter that they are negative...there are 129 of them.  How many numbers are there when you count from 0 to 136?  136, right? 
 
So if there are 129 numbers to the left of 0 and 136 numbers to the right of zero, in order to find how many degrees difference you simply need to add 136 and 129 to find out how many numbers there are all together between the two....
 
***Now lets use math to find your solution.  Remember that a positive minus a negative equals a positive....so a positive minus a negative can be exchanged with plus a positive.  Let me explain.
 
For example:  7- (-4) can also be written as 7 + 4 as the minus a negative, or two - signs beside each other, can be flipped to a plus sign. 
 
When we see the word 'difference' in a word problem, it usually means to subtract.  So that leads us to putting the following problem together:
 
136 - (-129)
 
Since this is a double negative, we flip it from minus a negative into plus a positive, making the problem read 136 + 129, just as we saw with our number line.  Both methods give us the same answer!!***
 
When you are looking for the difference between the two, you need to consider that they are each on different sides of a number line. Think about how many degrees are between the positive 136 degrees and the zero mark (136) and how many degrees are between the -129 degrees and the zero (129). In order to know the difference, you have to cover all the degrees that it took between the positive 136 and zero, as well as the degrees between the zero and the negative 129 degrees.
 
Therefore, you add both of them to get your total difference (and ignore the negative and positive, because now you're counting degrees as units, regardless of being above or below zero)
 
136 + 129 = 265 degrees
Hi Nikki;
136-(-129)
Subtracting a negative number is the same as adding a positive number...
136+129=265 degrees of difference