Answer:
A. 10.4
Step-by-step explanation:
Supplementary means to add to 180. Take 128 from 180 (180-128) and you get 52. 52/5= 10.4. To check this work you can solve it with the value plugged into the equation. 128 + 10.4(5) = 180, therefore 10.4 is the correct answer.