4/26 can be simplified by 2. So, this is not the answer.
8/21 cannot be simplified. So, it is one of the answers.
6/19 cannot be simplified. So, it is one of the answers.
9/10 cannot be simplified. So, it is one of the answers.
10/22 can be simplified by 2. So, this is not the answer.
So, the fractions in simplest forms are 8/21, 6/19, and 9/10.
Remark
You have to read this carefully to know what way to write it.
One way you could write it would be
20 * x = 18 where x is the fraction. Now all you need do is divide.
Divide both sides by 20
20/20 * x = 18/20

But you should reduce this fraction. The way to do that is to factor 18 and 20 into primes.
18: 2 * 3 * 3
20: 2 * 2 *5
Cancel out the Highest common factor or 2.
You are left with
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