67.7=60.7t-5t^2

Solution for 67.7=60.7t-5t^2 equation:

67.7=60.7t-5t^2

We move all terms to the left:

67.7-(60.7t-5t^2)=0

We get rid of parentheses

5t^2-60.7t+67.7=0

a = 5; b = -60.7; c = +67.7;
Δ = b2-4ac
Δ = -60.72-4·5·67.7
Δ = 2330.49
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{-(-60.7)-\sqrt{2330.49}}{2*5}=\frac{60.7-\sqrt{2330.49}}{10}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60.7)+\sqrt{2330.49}}{2*5}=\frac{60.7+\sqrt{2330.49}}{10}
$