A number line starts with 7 and ends with 9. in between are 7 marks. The letter A ia above the 5th mark. What is the value of A

Why not just draw it, there aren't that many

draw a line and mark off 2 units labeling them
7 , 8 and 9
now mark each part into 4 divisions, so now you have the segment from 7 to 9 marked off in quarters of a unit.
Count the marks between 7 and 9.
Aren't there 7 marks?
Isn't each part 1/4 units of length?

Can you label the 5th one?