(-1) - (-9)

(-1) - (-9)

 

Think of negative numbers as COLD numbers (the freezer has a negative temp)

an positive numbers are HOT numbers.

 

Here you have  a temp of -1  you want to take away some cold (because -9 is a cold number)

 

If you take cold out of a room then the room gets warmer!

 

So take away a negative can replaced by adding.

 

Taking  away some cold air has the same effect as adding some warm air.

 Both times the room gets warmer.   Do you get it?

 

      - - = + + = +

so

(-1)-(-9) = (-1) + (+9) = -1+9 = 8

 

or

(-1)-(-9) = -1 - -9 = -1+9 = 8