What is the slope of the line described by the following question?
-x+1/3y=5?

By rearranging the equation, the slope can be directly read from it.

You said                   -x + 1/3 y  =         5

Add 'x' to each side:        1/3 y  =    x + 5

Multiply each side by 3:        y  =  3x + 15

This form of the equation is the so-called "slope / intercept form",
because the numbers on the right side are the slope and intercept
of its graph.

When the equation is graphed, the y-intercept of the line is 15,
and the slope of the line is  3 y-units per x-unit.