Quadratic equation and algebra to solve geometrics

Hello

If anyone takes the time to read my questions, thanks a lot :)

1) A park is 480m long by 320 wide. It is decided to double its area retaining the rectangular shape, by adding strips of equal width to one end and one side. Find the length of the strips.

--> I thought iIwas doing this right by going (480+x)(320+x)= 2Area but in the end after doing the quadratic equation I somehow got a strange answer

2)A strip of metal 8cm wide is to be bent into a trough of rectanglular cross-section (open top) whose cross sectional area is 7.5cm2. Find the depth and width of the trough

Thanks a lot everybody:):)