What is the overall trend shown in this graph?  
how does a melting glacier affect the ocean?

The answer is 4 666666666666666fcx

Explanation:

You go two up for the numbers or 2 * 2 = 4, 3 *2 = 6, then replace. For the letters you just change it to the letter from the right of that letter on your keyboard.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.