A student earns $0.65 for each mistake she finds in a text. Sketch the equation of direct variation.

Question

An equation of direct variation is of the form
M = k X
where k us a constant. In your case M might be total money earned and X is the number of students.

Clearly M = 0.65 X

The graph is a straignt line through the origin with slope 0.65. It goes through the points
M = 0, X = 0 (the origin)
and
M = 13, X = 20