[1] Complementary means the angles will add up to 90 degrees
 () Blank one is BOC
 () Blank two is 90
 () Reason blank I am unsure as I do not know the wording that is being looked for, but it is either "given," "complementary angles" or something similar
[2] Since AOC is equal too BOC + 30, we can decide the following is true
 () First blank is BOC
 () Second blank is 30
[3] 30°
 () BOC + BOC + 30 = 90 [Given]
 2(BOC) = 60 [Subtract 30 from both sides & combine like terms]
 BOC = 30 [Divide by 2]
[4] 60°
 () 90 - 30 = 60
Have a nice day!
 I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather