Area of the shaded region = Area <span>of a square - Area of a circle
</span>
Side of a square = 2r
Area of a square = (2r)² = 4r²
Area of a circle = πr²
Area of the shaded region = 4r² - πr² = <span>r²(4-π)</span>
McKenzie's work is correct because on step 3 she added the A and the B correctly.
1. False because a rational is a fraction or part of a number (

).

2. True; a real number is any number that isn't imaginary (

)
3. True; same reason
4. True; an integer is any number that can be wrote without a fraction or decimal (the opposite of rational).
5. True;

and that's a decimal.
6. True; the natural number system starts from 0 and counts upwards
7. True; reason above
the answer of 2x +y = 20 ; 6x -5y =12
{ explained in image}