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Adding and subtracting numbers with double signs

Jonathon has $10 and has borrowed $12 from Stephen. But Stephen has cancelled Jonathon's debt so Jonathon can keep the $12 he borrowed. The mathematical expression is given below.

So Jonathon has $22. So when we cancel a debt it is like giving money to the person. In other words two negative signs make a positive.

There is another rule. If a positive and negative sign are next to each other we can change both of them into one negative sign.

One more rule. Two positive signs form a positive.

Look at the example below.
Exercise
Solution
Answer
1) 8 - -3 + -4 =
2) 3 - +4 + -4 =
3) -3 - +4 =
4) -9 + -6 - -8 =  
5) 13 + -8 - -9 =  
6) 19 - -23 + -11 - -4 =  
7) 12 - -23 - +4 =  
8) -10 - +4 - -12 =  
9) -5 + -4 - -3 - +12 =  
10) -12 + -23 - -14 =  
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