I believe the previous answer is not correct.
Let x = the amount of water you are going to add.
You are adding 100% water to a solution that has 55% water to get a mixture that will have 60% water.
1x + 89(.55) = .6(89 +x)
In the equation above, 1x represents the 100% water, 89(.55) represents the current amount of water in the solution and .6(89+x) represents a 60% solution that combines the 89 liters with the water.
Solve this to get 11.125 liters of water.
The total amount of solution is 100.125
To check, realize that the amount of saccharine has remained constant.
So 100.125(.40) should equal 89(.45).
They both = 40.05
So again, the amount of water needed to ADD is 11.125 and the total amount of solution after adding the water is 100.125