The standard deviation is the square root of the variance.
The answer is 75
First you subtract 180 and 165 to find that smallest angle inside the triangle(15). Then you add 15 and 90,the two angles you know, and do 180 - 105= 75.
The trick is that all angles inside a triangle equal 180 degrees. Hope this helps!
2/3 would be the correct answer.
X= 27
Because
3x−4y=65
(3x−4y)+4y=65+4y
3x−4y+4y=4y+65
3x=4y+65