If a relationship between two quantities is not proportional then when the fraction is reduced there should not be an equal ratio and the graph should not be a line that passes through the origin.
The graph of a proportional relationship is a line through the origin. When ratios between quantities are not constant, a relationship may be linear but not proportional and the graph does not pass through the origin. Example : ... Explain why the relationship between number of tickets and total cost is not proportional.
So if it does not pass through the the origin, it’s not proportional.
