What mass of table salt is required to be added to 250 g of a solution of the same salt with a mass fraction

What mass of table salt is required to be added to 250 g of a solution of the same salt with a mass fraction of 10% to obtain a salt solution with a mass fraction of 18%?

Solution:
1. Let’s designate: x – the mass of sodium chloride, which must be added to the original solution.
2. Find the mass of table salt in the original solution:
250 * 0.1 = 25 grams
Thus, the mass of table salt in the final solution is 25 + x grams. The mass of the entire final solution is 250 + x grams.
3. According to the condition of the problem, an equation was drawn up:
(25 + x) / (250 + x) = 0.18;
25 + x = 0.18 * (250 + x);
25 + x = 45 + 0.18x;
x – 0.18x = 45 – 25;
0.82x = 20
x = 20 / 0.82;
x = 24.4
Answer: 24.4 grams of table salt must be added to the original solution.