We can't do much with this info.
ASSUMING the second rect.'s height is half of the first's, then we can start.
The purple is area 10, and the triangle is 1/4 of the rectangle,so the larger one has... 40!
based on the image we can guess rect2's length is 1/2 rect1, so it's area is 1/4 rect1.
40/4 = 10/
40+10 = 50
Of course this is based on visual and isn't recommended, but there's no other clues as to similar objects, etc.
Ask if you don't understand anything.