Write the following as an equation in two variables:
$\pi x = 3.14$

(A) linear equation in two variables is expressed in the form $ax + by + c = 0$,where $a$,$b$,and $c$ are real numbers and $a$ and $b$ are not both zero.
Given the equation $\pi x = 3.14$,we can rewrite it by bringing all terms to one side:
$\pi x - 3.14 = 0$.
To express this in the form $ax + by + c = 0$,we include the $y$ term with a coefficient of $0$:
$\pi x + 0y - 3.14 = 0$.