Y = kx is the direct variation equation with k being the "constant of variation"
The constant here being the conversion decimal .91
y = 0.91x
Is there another part of this?
The standard form of a line is in the form

A, B and C are integers, and A is positive. Let's start with multiplying the whole equation by 3 to get rid of denominators:

Subtract 3y from both sides:

Which of course is equivalent to

Which is the standard form, given the coefficients A=1, B=-3, C=6.
Answer:
72 degrees.
Step-by-step explanation:
If the angle is x degrees its complement is 90-x degrees and it's supplement is 180-x degrees.
4(90-x) = 2/3(180 - x)
360 - 4x = 120 - 2/3 x
360 - 120 = -2/3 x + 4x
240 = -2/3 + 12/3 x
240 = 10/3 x
x = 240 * 3/10
x = 72 degrees.

and surely you know how much that is.