To make an equation that solves for the height as according to the volume of a pyramid, you must isolate the variable h on one side.
The first thing you have to do is to multiply both sides by 3 to get 3V=Bh.
Then, divide both sides by B to get your answer as h=3V/B.
I think the graph below is correct.
The final price is the cost plus the tax.
Since we know the tax and a percent, we can write this as
T = C(1+r)
T = what Graham paid = $87.45
C = cost before tax
r = tax rate expressed as a decimal = .40
Plugging in what we know
87.45 = C (1+.4)
87.45 = C(1.4)
Divide both sides by 1.4
C = $62.46
