Answer:
4500
or 4712.39
What we need to know: The formula for the volume of a cone is: 
So we are solving for V
Step-by-step explanation:
1) Radius is half of diameter r=30/2 thus, your radius is 15
2) you then have all your variables so you can start plugging values into your equation:
r=15 h=60

This would be your exact answer but if you are solving for a rounded answer it would be
V~4712.39
First, let's create an equation for this problem.
($70 × 4) + $40
Now, all you would have to do is solve it using the order of operation (PEMDAS).
($70 × 4) + $40 = $280 + $40
$280 + $40 = $320
The plumber charged $320.
I hope this helps!