There are a lot of rational number between 7.7 and 7.9, but the problem asked to find only one ratio number, so I will choose one which is 7.8. 7.8 is a rational number because ration number means that it can change into a fraction or improper fraction.
Now, let's change 7.8 into the fraction
First of all, change this into mixed number:
7.8
=7 8/10
=7 4/5
Then, change this into improper fraction.
Step 1:
Numerators:
7×5+4=39
Step 2:
Denominator
5, so your final answer will be 39/5. Hope it help!