18=-2.7t^2+30t+6.5

Solution for 18=-2.7t^2+30t+6.5 equation:

18=-2.7t^2+30t+6.5

We move all terms to the left:

18-(-2.7t^2+30t+6.5)=0

We get rid of parentheses

2.7t^2-30t-6.5+18=0

We add all the numbers together, and all the variables

2.7t^2-30t+11.5=0

a = 2.7; b = -30; c = +11.5;
Δ = b2-4ac
Δ = -302-4·2.7·11.5
Δ = 775.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-\sqrt{775.8}}{2*2.7}=\frac{30-\sqrt{775.8}}{5.4}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+\sqrt{775.8}}{2*2.7}=\frac{30+\sqrt{775.8}}{5.4}
$