40×30×4+50 40
=4800+2000
=6800 (square centimeter)
2、
40 liters =40 cubic decimeters = 40,000 cubic centimeters.
=40000÷(50×40)
=40000÷ 2000
=20 cm
3、
2.5×50×40
=250×40
=5000 (cubic centimeter)