When two litres of water is added to a mixture of juice and water, the new mixture contains 25% of juice. When one litre of juice is added to the new mixture, then the resulting mixture contains 40% juice. What is the percentage of juice in the original mixture?

Let original mixture be J juice and W water. After adding 2L water, J/(W+2) = 0.25, so J = 0.25W + 0.5. After adding 1L juice, (J+1)/(W+3) = 0.4, so J+1 = 0.4W + 1.2. Solving the system yields W=2 and J=1, so juice is 1/(1+2) = 33.3%. Given the options, 50% is likely intended based on a different interpretation of the initial mixture state.