How many litres of pure antifreeze should be added to 5 litres of 30% antifreeze solution to create a 65% antifreeze solution?

0.65% of new amount=old amount of 30% plus amount of new

0.65 (x+5) = 5 (0.3) + x

solve

distribute

0.65x+3.25=1.5+x

minus 1.5 from both sides

0.65x+1.75=x

minus 0.65x both sides

1.75=0.35x

divide both sides by 0.35

5=x

5 liters of pure should be added