Question

explain how you know 21/100 is greater than 1/5

Answer 1

simply change the denominator to match 100. that means multiplying the fraction by 20/20. so 1/5 becomes 20/100.
20/100 < 21/100

Answer 2

Answer:

You know that 21/100 is greater than 1/5, because you can multiply 1/5 times 1, choosing the proper expression of 1, and then compare it with 21/100.

Step-by-step explanation:

We are using simply arithmetic, but in order to ensure that an inequality is fullfilled, we have to be able to compare trivial things.

In this case, if we multiply 1/5 times 1, we get 1/5 again, but written in a better expression to compare it with 21/100... Let's see:

$\frac{1}{5}=\frac{1}{5}*1=\frac{1}{5}*\frac{20}{20}=\frac{20}{100}$

and now, let's compare trivial things (in this case, trivial comparison of numbers):

$\frac{21}{200}>\frac{20}{100}\Leftrightarrow\frac{21}{200}>\frac{1}{5}$

which is the correct answer to the problem.