Assuming that we want the price to be proportional to the volume...
The volume of a cylinder is given by pi*r^2 * h where r is the radius and h is the height
So the volume of the smaller can is given by
pi*(3cm)^2 *(12.5cm)= 353.42 cm^3
And the volume of the larger can is given by
pi*(18cm)^2 *(37.5cm) = 38170.35 cm^3
So...using a ratio...
38170.35/353.42 = x/.35 where x is the price of the larger can = $37.80
Wow!!...that's a pretty pricey can of cola....but...it IS a party, after all!!