Let no. of shirts be x.
Chris -- 7x
Brian --- 5x
132x/(7x+5x) = 11
x=11
Chris sold (11 x 7) shirts = 77 shirts
Brian sold (11 x 5) shirts = 55 shirts
The simplified expression is
and the restriction is 
<h3>How to simplify the expression?</h3>
The expression is given as:

Express x^2 - y^2 as (x + y)(x - y) and factorize other expressions

Rewrite the expression as products

Cancel out the common factors

Express 4x^2 - y^2 as (2x - y)(2x + y)

Cancel out the common factors

Take the LCM

Hence, the simplified expression is
and the restriction is 
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Answer:
£100
Step-by-step explanation:
if the ratio is 7:3, the difference between them is 7-3 . = 4.
So,
4x = £40
Now, calculate x
x = £10
Now,
we are able to calculate:
7x (Bridget's share) = £70
3x (Caroline's share) = £30
Sum = £100
Hope this helps.
Good Luck