Given:
In the given triangle,
With respect to y, Perpendicular = 10 cm and Base = 8 cm
To find the value of y.
Formula
By Trigonometric Ratio we get,

Now,
Putting the values of perpendicular and base we get,

or, 
or, 
Rounding off to the nearest tenth, we have;

Hence,
The value of y is 51.3°.
Answer: 180
Angles in a linear pair are always supplementary. This means they form a straight angle or a straight line.
I can't see the options, but you would need to multiply (4x - 2y = 7) by 3, and (3x - 3y = 15) by 4 so that you get 12x in both equations. Then when you subtract, you eliminate 12x. I hope this helps!
A right angle is 90 degrees, so five-thirds of a right angle is 90*5/3=450/3=150 degrees.