if multiplying by 1.05 finds 5% and adds it on, what number would find 8% and take it off?

If you want to remove 8% from x, find 0.92 · x.

You use 0.92 because 100% - 8%  =  1.00 - 0.08  =  0.92.

Example:  Reduce $175.00 by 8%   --->   $175.00 x 0.92  =  $161.00.