-1.3=7t-5t^2

Solution for -1.3=7t-5t^2 equation:

-1.3=7t-5t^2

We move all terms to the left:

-1.3-(7t-5t^2)=0

We get rid of parentheses

5t^2-7t-1.3=0

a = 5; b = -7; c = -1.3;
Δ = b2-4ac
Δ = -72-4·5·(-1.3)
Δ = 75
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{75}=\sqrt{25*3}=\sqrt{25}*\sqrt{3}=5\sqrt{3}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-5\sqrt{3}}{2*5}=\frac{7-5\sqrt{3}}{10}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+5\sqrt{3}}{2*5}=\frac{7+5\sqrt{3}}{10}
$