Answer
$6.4$ft or $6\frac{2}{5}$ft
Work Step by Step
The formula given to us is very simple: $w_{1}*x_{1} = w_{2}*x_{2}$
We know:
$w_{1} = 100$
$x_{1} = 8$
$w_{2} = 125$
So lets plug that into our equation and solve:
$100*8 = 125*x$
$800 = 125x$
$\frac{800}{125} = x$
$6.4 = x$
