Question 65511
Let x ltrs of pure alcohol solution be added to 50 ltrs of a 25% alcohol solution to obtain a 45% solution.

==> the equation would be:

x*1 + 50*(0.25) = (50+x)*(0.45)
==> x + 12.5 = 22.5 + o.45 x
==> x - 0.45x = 22.5 - 12.5
==> 0.55x = 10
==> 0.55x/0.55 = 10/0.55
==> x = 18.18

Thus 18.18 ltrs of pure alcohol solution be added to 50 ltrs of a 25% alcohol solution to obtain a 45% solution.

Good Luck!!!