To solve #-2-1+6#, you must simplify the problem using the steps below.
First, you must focus on one section of the problem. We are going to start with # color(red)((-2-1))+6#. If you break this apart, and pretend that for the moment, the #+6# isn't even there.
So, to simplify #-2-1# you can think of it as #2+1#, but with a negative sign in front of it. Then, you will end up with #color(blue)(-3)#.
Now, the #+6# can be added back in, but the #-2-1# can be replaced with -3, as that is what we got above. So the equation that you have is #-3+6#.
For this, you can use the commutative property of addition, which means that the order of the numbers can be changed. The grouping must stay the same though. You can think of it like this: #(-3)+(6)#. The commutative property, says that it can be re-written like this: #color(red)(6-3)#.
So, subtract #6# from #3#, and you get #3#. Therefore, #-2-1+6# simplified, is #color(blue) 3#/
