The answer is 2, because it is asking you, out of the 30 people, who is being counted twice for brown hair and blue eyes. Therefore, you add 17 and 15 to get 32, and because there are only 30 people in the class, you do 32 - 30 = 2 people. Let me know if you're confused or anything :)
Use the rule of <em>SINE(A+B)= SINACOSB+COSASINB</em>
:. SIN(23pi/4+11pi/6)
-add both fractions
:. SIN(138pi/24+44pi/24)
-Simplify
:.SIN(182pi/24)
And simplify again the fraction
:.SIN(91pi/12) ---------Final answer
Could you add some more details about the problem?
You set it up as a y=mx+b problem 150=55x+40 then you subtract 40 from 150 making 110=55x so x=2