I'll heart/Like and rate 5 stars po if the answer is right :)

4.) 8978 - 8112 = 866
5.) 1876 - 1753 = 123
6.) 7872 -7771 = 101
7.) 5674 - 5585 = 89
8.) 4955 - 4934 = 21
-computing water consumption is only subtracting the given present reading and previous reading together ;)