Find an angle between 0 and 2π that is coterminal with 27 pi/10

27pi/10 *180/pi= 486, but since we want a coterminal angle between 0 and 2pi we substract 360, 486-360= 126 (this is the answer in degree form), =126* pi/180= 7pi/10
to make sure this is the right answer we have to check if the reference angles are the same, which is this case they are. (180-126= 54) (540-486=54)

Ibelieve the answer is c i worked it out three times but if my answer is wrong someone correct me

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.