Question 43441
First, write the equation of proportionality:
Since the income tax, y is directly proportional to the gross income, x, you can write:

y = kx where k is the constant of proportionality:

To find the value of k, just substitute the given values of y (state income tax = $43.50) and x (gross income = $1500) and solve for k.

$43.50 = k($1500) Divide both sides by $1500.
k = 0.029

The final equation is then:

y = 0.029x