Which one is it? will mark brainliest

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.

Find the simple interest earned to the nearest cent for each principal, interest rate, and time 735 7% and two and a half years

Find a number such that if you add 8 and divide the result by 4 you will get the same answer as if you subtracted 3 from the original number and divided by 2