Ability to solve proportions can be useful in everyday life.

Let's say you have in the kitchen vinegar essence containing 40% vinegar, and you need a 6% vinegar.

Without drawing proportions here can not do.

You will need

- handle, piece of paper, analytical thinking

instructions

1

We write the condition of the problem. 40% vinegar is 100%, you need to find how to take the vinegar for 6% vinegar. This will be x. We write two equations: 40% = 100%, x = 6%.

2

Get proportion: 40/6 = 100 / x.

6 Multiply by 100 and divide by 40.

3

We find that vinegar essence 15% of the total water-vinegar solution.

That is, you can take 15 ml of vinegar and 75ml of water to give approximately 100 ml of 6% vinegar. About - because the water has a replacement property, and the output of different solutions can turn a bit less than originally planned.

4

The task is more difficult. There buckwheat flour with a protein content of 12.6 her g per 100 g dry product. And there is a starch with a protein content of 1 g per 100 g dry product. It is necessary to make starch-flour mixture with 2 g protein per 100 g dry product.

5

Take for x in the mixture of starch in grams per (100-x) buckwheat flour content in the mixture in grams.

6

Then x * 1/100 - how many grams of protein accounted for starch, 12.6 * (100-x) / 100 - how many grams of protein accounted for buckwheat flour.

In sum, these fractions are 2 grams of protein per 100 g of mixture.

7

Solving the equation, we see that to obtain a mixture containing 2 g of protein, we need to take 91 grams of starch and 9 g of buckwheat flour.