The answer to 18m + 27n would be
All triangles add up to 180 degrees. Since sines can't be a negative, you need to add -130 to 180. The answer to this question would be sine 50 degrees.
1 yard = 3 feet
Divide 34 by 3, you should get 11 and 1/3.
So the classroom is 11 1/3 yards long, but 1/3 of a yard just so happens to be one foot, as 3 feet is 1 yard.
That means that the classroom is 11 yards and 1 foot long, or answer choice B.
Hope this helps! :)
11 is the coefficient of r and 7 is the coefficient of s