We're being asked to just distribute the negative sign. Based on PEMDAS, we can say that the (d-e) is what we should evaluate first, because every time you go a step deeper you run into a parenthesis until this part, so:
[tex] a-(b-(c-d+e-f)-g) [/tex]
Next we go to the inner most parenthesis, which is the c-d+e+f part:
[tex] a-(b-c+d-e+f-g) [/tex]
And now we just distribute the last negative to conclude:
[tex] a-b+c-d+e-f+g [/tex]
