5.5=-2.7x^2+40x

Solution for 5.5=-2.7x^2+40x equation:

5.5=-2.7x^2+40x

We move all terms to the left:

5.5-(-2.7x^2+40x)=0

We get rid of parentheses

2.7x^2-40x+5.5=0

a = 2.7; b = -40; c = +5.5;
Δ = b2-4ac
Δ = -402-4·2.7·5.5
Δ = 1540.6
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{-(-40)-\sqrt{1540.6}}{2*2.7}=\frac{40-\sqrt{1540.6}}{5.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+\sqrt{1540.6}}{2*2.7}=\frac{40+\sqrt{1540.6}}{5.4}
$