If each painting takes 3 hours, and he has to do 8 then he would spend 24 hours doing all 8 portraits
In any cyclic quadrilateral, angles opposite one another are supplementary, meaning

and given that
, we have
.
By the inscribed angle theorem,


and since

we have

and it follows that

Let length of the hypotenuse = 3x and length of given leg be x feet.
then (3x)^2 = x^2 + 648
8x^2 = 648
x^2 = 81
so x = 9 and 3x = 27
Hypotenuse is 27 feet and the leg equals 9 feet.
You would just need to make an inequality from the description. You would make "x" the number. The answer would be "x-4>-1"