Maths urgent help needed!
posted by joi .
A rectangular tank measures 60cm by 40cm by 30cm. It is half filled with water. Water is added to the tank at a rate of 13litres per minute and drained out at 9litres per minute. Find the volume of water in the tank after 7 minutes.

You already have 60x40x15
or 36000 cm^3 in the halffilled tank
or you have 36 L in the halffilled tank
The net increase from that point on is 4 L/min
So in the next 7 minutes, 28 L are added
Total volume = 36+28 = 64 L 
thanks, just double checking to see if i got it right.