I want to make this clear, this is NOT MY ANSWER! Someone else has already answered this question on here I'm just pasting their answer here so you can get the full details on how it was solved.
We know that 1/5 > 1/6 > 1/7
If we change the numbers to decimals we can see what decimals we can use that are between the number 1/5 and 1/7 .
1/5=.20
1/7≈.14
We can use any number between these two decimals to create a fraction. Let us use .16
.20>.16>.14
Now we can change that number to a fraction.
.16=16/100 which reduced to 4/25
Let's verify:
1/5 > 4/25 > 1/7 find LCM
35/175 > 28/175 > 25/175
One fraction that is between 1/5 and 1/7 that does not have a denominator of 6 is 4/25.