# How many grams of 50% and how many grams of a 20% acid solution do you need to take to get 900

**How many grams of 50% and how many grams of a 20% acid solution do you need to take to get 900 grams of a 30% solution?**

To solve this problem, you first need to find the mass of acid in the resulting solution.

To do this, multiply its mass, namely 900 grams by the percentage of acid.

Will be:

900 * 30% = 900 * 0.3 = 270 grams.

We draw up an equation in which we write the mass of 1 solution as x, and the weight of the second solution as y.

We get:

x + y = 900.

0.5 * x + 0.2 * y = 270.

Express x from the first equation and substitute it into the second.

x = 900 – y.

0.5 * (900 – y) + 0.2 * y = 270.

450 – 0.5 * y + 0.2 * y = 270.

0.3 * y = 180.

y = 180 / 0.3 = 600 g (second solution).

x = 900 – 600 = 300 g (first solution).

Answer: 300 and 600 grams, respectively.