Question 1188338
the solution is 20% salt by mass.
the total solution is 700 grams.
20% * 700 = .20 * 700 = 140 grams of salt.
the rest is water.
80% * 700 = .80 * 700 = 560 grams of water.


if 300 grams of water is evaporated, the solution is left with 260 grams of water and 140 grams of salt.


the percent of salt now becomes 140 / (140 + 260) = 140 / 400 = .35 = 35% salt by mass.