0.8t(10-t)=10

Solution for 0.8t(10-t)=10 equation:

0.8t(10-t)=10

We move all terms to the left:

0.8t(10-t)-(10)=0

We add all the numbers together, and all the variables

0.8t(-1t+10)-10=0

We multiply parentheses

0t^2+0t-10=0

We add all the numbers together, and all the variables

t^2+t-10=0

a = 1; b = 1; c = -10;
Δ = b2-4ac
Δ = 12-4·1·(-10)
Δ = 41
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{-(1)-\sqrt{41}}{2*1}=\frac{-1-\sqrt{41}}{2}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{41}}{2*1}=\frac{-1+\sqrt{41}}{2}
$