Ok. So we are going to multiply 500,000 and .19
Personal use: 500,000*.19=95,000
Industrial use: 500,000*.42=210,000
In this work, it shows that there is more used for industrial use than for personal use.
But none the less. We are going to subtract this. 210,000-95,000=115,000. 115,000 more gallons are used for industrial use than for personal use.
I hope this helps, if you have any other questions on this or any other question, just ask. I am here to help you as needed.