y=21.665x^-0.264
find x if y=50
Set y to be 50 and then take logs of both sides.
50 = 21.665x-0.264
ln(50) = ln(21.665) - 0.264lnx using the properties of logs.
Rearrange: lnx = (ln(21.665) - ln(50))/0.264
x = e(ln(21.665) - ln(50))/0.264