Intermediate Algebra: write (-6 + 7i) - 9 in form 'a + bi'

[Helen]

Can I get some help with this?
Add or subtract, write the answer in the form a + bi.
(- 6 + 7i) - 9
This is what I did.
(- 6 + 7i) - 9 = (- 6 + - 9) + (7 + - 9)i = 15 - 7i
Am I working this right?

 

[tkhunny]

Re: Intermediate Algebra

No, sorry.

Add Real parts to Real Parts and Imaginary Parts to Imaginary Parts.

How did you get 15, anyway? -6 - 9 = -15.
How did you get -7i, anyway? 7 - 9 = -2.

(-6 + 7i) - 9 = (-6-9) + 7i = -15 + 7i

 

[Helen]

tkhunny,
Thank you for your help. Very much appreciated. Helen