Tank A holds 7145 ml of water and Tank B holds 7747 ml of water. The water from both tanks is poured into Tank C which is empty. What is the volume of water in Tank C, rounded off to the nearest hundred ml ?
There is a calculator on the home site - just add the two together. That is assuming that tanks A and B were full to start with and tank C was empty.
Here's the homepage if for some reason you can't find it. :)
http://web2.0calc.com/