40=0.6x^2-17x

Solution for 40=0.6x^2-17x equation:

40=0.6x^2-17x

We move all terms to the left:

40-(0.6x^2-17x)=0

We get rid of parentheses

-0.6x^2+17x+40=0

a = -0.6; b = 17; c = +40;
Δ = b2-4ac
Δ = 172-4·(-0.6)·40
Δ = 385
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(17)-\sqrt{385}}{2*-0.6}=\frac{-17-\sqrt{385}}{-1.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(17)+\sqrt{385}}{2*-0.6}=\frac{-17+\sqrt{385}}{-1.2}
$