Let, total number of T-shirts are x.
Number of blue T-shirts = (2/3)x = 2x/3 .
Number of blue shirts on sale = (3/5)(2x/3) = 2x/5 .
Number of medium sized blue shirts on sale = (1/5)(2x/5) = 2x/25 .
Fraction of the shop's T-shirts are blue T-shirts that are on sale and are size medium = 
= 2/25 . ( Number of medium sized blue shirts on sale divided by total number of T-shirts )
Hence, this is the required solution.
Divide both sides by 5 to get t by itself, then you have your answer
Hmm question is a little confusing but fractions can be represented as division or a part of somthing, like 4 pieces of an 8 slice pizza, or you have 8 peices of pizza and you divide them by 4. Im pretty sure a rational number is any number that can be representated as a fraction. an irrational number is something you cant express as a fraction like the square root of a number or pi.
Let's calculate each area.
4 m:
We need to divide it by 2 to find the radius.
4÷2=2
Now let's put it in the formula.
2²π
4π=12.5663706≈13
6 m:
We need to divide it by 2 for the radius.
6÷2=3
Now put it in the formula.
3²π
9π=28.2743≈28
Now subtract 13 from 28.
28-13=15
So, the difference between their area is 15 m².
