H=-4.9t^2+49t+1.5=124

Solution for H=-4.9t^2+49t+1.5=124 equation:

=-4.9H^2+49H+1.5=124

We move all terms to the left:

-(-4.9H^2+49H+1.5)=0

We get rid of parentheses

4.9H^2-49H-1.5=0

a = 4.9; b = -49; c = -1.5;
Δ = b2-4ac
Δ = -492-4·4.9·(-1.5)
Δ = 2430.4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$H_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-49)-\sqrt{2430.4}}{2*4.9}=\frac{49-\sqrt{2430.4}}{9.8}
$
$H_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-49)+\sqrt{2430.4}}{2*4.9}=\frac{49+\sqrt{2430.4}}{9.8}
$