Absolutely not because
if you see as fraction
8/7 and 15/16 is not equal at all
if it had to be equal if should've been 16/14
Volume of a cone = (1/3) x Area of the base (B) x height(h)
V = (1/3)·420·180
= 25200 mm³
I believe that x=20 from the math i did hopefully its helpful.