I am a famous black mathematician whos work is in biomathematics, genetic variation and chaos theory. Who am I?

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?

How can you tell when x and y are not directly proportional?

What is the point slope form of a line with slope -5 that contains point (2,-1)