What is the slope of y= -4

Create a real-life situation and create a system and show how it might be modeled algebraically with a system of equations (or inequalities) show all work include a few sentences explaining the situation, your variables of choice and what each represents, and how you would set it up and solve it algebraically. !

Can someone explain to me how to do

Savannah had 40 iris blooms last year this year she had 15% more iris blooms how many more hours blooms did savannah have this year