<span>x : y is equal to 12 : 8. These can be reduced or cancelled down to 3 : 2 in the same proportions. Therefore, when y is 12, you have to multiply the smallest value y can be by 6, and must do the same to the smallest x value to retain the proportions. x = 18 when y = 12.</span>
Relative extrema occur where the derivative is zero (at least for your polynomial function).
So taking the derivative we get
<span>20<span>x3</span>−3<span>x2</span>+6=0
</span><span>
This is a 3rd degree equation, now if we are working with complex numbers this equation is guaranteed to have 3 solutions by the fundamental theorem of algebra. But the number of real roots are 1 which can be found out by using Descartes' rule of signs. So the maximum number of relative extrema are 1.</span>
So it would equal to 8/10 and divide by 2 which you would get 4/5