Yay! We're there! :)
Same as with the last question, you want to multiply top and bottom by the conjugate (if you don't remember what that is, take a look at the last question). In this question, the conjugate is (3-i). Therefore:
[tex] \frac{5+5i}{3+i} * \frac{3-i}{3-i} [/tex] ← FOIL this (If you would like a more in depth explanation for this, go ahead and comment. I feel like you got it, though)
[tex] \frac{(5+5i)(3-i)}{(3+i)(3-i)} = \frac{20+10i}{10} = 2+i [/tex] or D
