Here is the solution...
This is a proportional relationship.
A proportional relationship is nothing the two quantities vary directly with each other.
The proportional equation<em> y = k x</em>. where k is the constant proportionality.
This means that as <em>x</em> increases, <em>y </em>increases and as <em>x</em> decreases, <em>y</em> decreases.
Here we use the proportional relationship to find the equation.
The number of miles driven is proportional to the number of gallons of gas.
Therefore, the equation is Miles = k Gallons
That is <em>M = k G, </em>where k represents the number of miles driven per gallon of gas.