Please help me with my math problems

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?

Use set builder notation to represent the following set: { -3, -2, -1, 0}

You are measuring the dimensions of the floor in your bedroom because you are planning to buy new carpet. which unit of measure is the most appropriate to use in this situation?