The easiest way to do this would be to imagine that Jolie has 100 marbles. If Mary has 40% fewer, that means she has 60 marbles. Then if they combine all their marbles into a single bag, they will have 160 marbles, of which 100 are Jolie's. So the % that is Jolie's is 100/160 = 0.625 = 62.5%.
I think it would be $77.00
First find the area of the rectangle: 10 * 40 = 400
Now, since the square has the same area, we'll find the side lengths of the square by just finding the square root of 400 which is 20. You can do this with a calculator. So the side length of any side on the square is 20.