Chris and dan share £60 in the ration 2:3 how much will dan get

Icould really use some with this question.

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm

Let f(x) = 5/x and g(x)=2x2+5x. what two numbers are not in the domain of f o g