In order to determine what is the equation which describes the values of the table, consider that the general form of the equation is:
y = mx
where m is the constant of proportionality between both variables x and y.
To calculate m you calculate the quotient between any pair of data from the table.
If you for example use the following values:
Students = 8.00
Lunch cost = 2
the constant of proportionality is:
m = 8.00/2 = 4.00
Next, you replace the value of m in the equation y=mx:
y = $4.00x
