100=0.16b^2

Solution for 100=0.16b^2 equation:

100=0.16b^2

We move all terms to the left:

100-(0.16b^2)=0

We get rid of parentheses

-0.16b^2+100=0

a = -0.16; b = 0; c = +100;
Δ = b2-4ac
Δ = 02-4·(-0.16)·100
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-8}{2*-0.16}=\frac{-8}{-0.32}
=+25
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+8}{2*-0.16}=\frac{8}{-0.32}
=-25
$