P(x)=60x-0.3x^2-3x+15

Solution for P(x)=60x-0.3x^2-3x+15 equation:

(P)=60P-0.3P^2-3P+15

We move all terms to the left:

(P)-(60P-0.3P^2-3P+15)=0

We get rid of parentheses

0.3P^2-60P+3P+P-15=0

We add all the numbers together, and all the variables

0.3P^2-56P-15=0

a = 0.3; b = -56; c = -15;
Δ = b2-4ac
Δ = -562-4·0.3·(-15)
Δ = 3154
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-\sqrt{3154}}{2*0.3}=\frac{56-\sqrt{3154}}{0.6}
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+\sqrt{3154}}{2*0.3}=\frac{56+\sqrt{3154}}{0.6}
$