Please help me to do this task please don't send me links because I expect you to help me please help me I am gonna apreciate your help. ​

The graph below shows the amount of money left in the school’s desk fund, f, after d desks have been purchased. for each new desk that is purchased, by how much does the amount of money left in the school’s desk fund decrease?

If you can solve all of these i will give ! - 4% of 190 - 4% of 162.5 - 4% of 140 - a 4% increase from 155.1 - a 4% increase from 159.8

Ineed with math stuff it involves graphs