help

it makes the equation ((0.1x)+30*50%)/(x+30)=0.2 to get (0.1x+15)/(x+30)=0.2 so x=90

x = amount of 10%

amount of alcohol   =   .1x         in the 30 l  there is  .5 (30) of alcohol

final alcohol amount will be   .2 (30 + x)

sooooo

.1x      + .5(30) =  .2 (30 + x)    Solve for 'x'   the amount of 10% needed