Perimeter is the sum of all the sides. So we can set up an equation:

Now solve for 'x', combine like terms:
When it comes to terms with variables it's just like normal addition but we keep the variable:


So we have:

Add:

Subtract 7x to both sides:

Subtract 4 to both sides:

Divide 5 to both sides:
Volume of a cone = (1/3) x Area of the base (B) x height(h)
V = (1/3)·420·180
= 25200 mm³
The answer is -(5x+16/x^2-22)