1 contains 30% salt, so the salt is120 * 30% = 36g. To become 40%, the total amount of brine should be 36/40% = 90g, so120-90 = 30g of water should be evaporated.

2 suppose x grams 10% sugar water is needed, then the added sugar is 10%x grams. Since there is sugar120 * 30% = 36g, there is sugar 0.1x+36g in total. The original solution is 120g, plus x gram solution, there will always be 120+x gram solution, so there will be (0.1x+36)/(120+x) = 20%, and X = 65438.

Of course there are two kinds. Is the way to ask the first two questions.

(1) If water is evaporated, the raw sugar is 60 * 20% = 12g, and the required concentration is 40%, then the evaporated solution should be 12/40% = 30g, so the water to be evaporated is 60-30 = 30g；;

(2) increase the concentration of sugar water. I don't know how much sugar water you want to add here, for example, add 50% sugar water, so suppose you want to add x grams of this sugar water, or as in the second question, get the equation:

(50%x+ 12)/(60+x) = 40%，x = 120。

If you want to add other high-concentration sugar water, just replace that concentration with 50% here. Note that the added sugar water concentration must be higher than 50%, because to obtain 40% sugar water, the original sugar water concentration is only 20%, which is lower than this target concentration. If you add a low concentration to a high concentration, you will always get a solution between the two concentrations.