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

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.

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:

`(1)/(5)=(1)/(5)*1=(1)/(5)*(20)/(20)=(20)/(100)`

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

`(21)/(200)>(20)/(100)\Leftrightarrow(21)/(200)>(1)/(5)`

which is the correct answer to the problem.