If l is parallel to m find 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.

Me. drysdale earned 906.25 in interest in one year on money that he had deposited in his local bank if the bank paid an interest rate of 6.25% how much money did mr. drysdale deposit

What expression is equivalent to (2x-1)(x-3)?