If you think of the "for every" as a : then it will make sense. So, replace the "for every" with a :.
So:
There are 5 strawberries for every 6 apples
Turns into
strawberries:apples = 5:6
The answer is D. 42
A triangle equals 180 in total so what you would do it subtract 122 from 180 because 180 is also the angle of a straight line. You would get 58 then you add 58 and 80 to get 138. Subtract 138 from 180 and you get your answer of 42