Answer:
b.
Step-by-step explanation:
The quantity x minus 2y is (x - 2y), then we add 3.
For this case we have that by definition, a linear equation is of the form:

The variable (s) involved in the equation always have exponent 1.
Some examples of linear equations are:

Answer:
In a linear equation the variables have exponent 1.

Answer:
0.0174 is the answer you are looking for
3x + 9 = 90
3x = 90 - 9 = 81
x = 81/3 = 27
x = 27