Another solution very simple good for buying

 The owner of the apartment where Valéria lives wants to increase the rent from R$400.00 to R$568.00.

The proposed percentage increase is:

b)42%

I gonna taught how to think and not use a formula:

Porcetagem the increase we will solve without formulas, simply applying what it means, the whole is 400,00 and 568,00 is the whole plus something and that something is 168,00 so far I have not used any formula I'm just telling you what is part of a whole, but it helps me to know in units of hundreds what 168 means for 400, for hundreds I work with that and values they are floating in other words they change, so hundred is tempestive, it is an occurrence used as standard.

So 168 is a part of 400, what do you do? You divide the part by the whole, that's right, you take the smallest and divide it by the largest, that will give you a fractional number less than one, exactly because it's part of a whole, you see that I said 1, it can only be a number less than one, so it's a fractional number less than one, but it's a teaspoon, fractional numbers are huge, there are thousands of them, so multiply by 100 and divide by 100, 100%, that's it, multiplying and dividing is built in, the number hasn't changed, it's just become more comprehensible, looking at it, do you know who 90% is, if it's 0.9 or 0.09 or 0.009, do you know if this 0.10 is 10 percent, 1 percent or 0.1 percent?

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