The ratio of the number of students in Mr. Johnson's class who brought lunch yesterday to the number of students who did not bring lunch was 4:7. Twelve students brough lunch. How many students were in Mr. Johnson's class yesterday

Ibelieve it’s 5 and then 3

Volume is length times width times height so
20 times 8 times 30 which is 4,800
surface area is ph (p is perimeter of base), h is height.
so perimeter would be length+length+width+width so 20+20+8+8 which is 56. so multiply 56 times 30 which is 1680. hope this !