This is for my calculus 1 homework review for a test coming up. Any help would be appreciated!!

5. You want to construct a series of pens as shown below in such a way that 3y + 6x = 255. Find the maximum possible area, A = xy. X6. The top hall of an hourglass is an inverted cone with an overall height of 15 cm and radius of 9 cm. Sand is falling into the bottom half at a rate of 10 cm3fsec. At what rate is the height of the sand decreasing when the sand is 7 em deep