Question

(-2)+(-4)+(-5)-(-6)-(+7)

Answer 1

(-2)+(-4)+(-5)-(-6)-(+7)

=-2-4-5+6-7
=-2-4-5-1
=-2-4-6
=-2-10
=-12

Answer 2

If it is a negative number, adding is just subtracting that number, but it is like adding because the numbers seem to be in ascending order.
So,
(-2)+(-4) = -6
(-6)+(-5)= -11

However, when subtracting negative numbers, it is the opposite.
(-11)-(-6)= -5

And subtracting positive numbers in the negative end of the number line is just adding if you ignore the minus sign on the front. 
Therefore,
(-5)-(+7)= -12

Hope it helps :D