Question 709962
So you want to remove v gallons of the low concentration mixture of antifreeze and replace it with v gallons of the pure 100% antifreeze.  You want the finished volume to be the same as before.  The current concentration as percent in the tank is {{{p[b]}}} and you want a finished concentration{{{ p[t]}}}.


{{{(8p[b]-vp[b]+v*100)/8=p[t]}}}

Find v.