What is the value of x?

Find the volume of the largest rectangular box in the first octant with three faces in the coordinate planes and one vertex in the plane x + 2y + 3z = 15.

Mama mia restaurant used 1 2 2 1 ? of their mozzarella cheese making pizza and the remaining 6 4 64 ounces making pasta. how many pounds of mozzarella cheese did mama mia start with?

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)