Answer: p = -0.004n + 8
Step-by-step explanation:
Consider the number of shirts & the price as an x,y - coordinate
4000 shirts at $32 --> (4000, 32)
5000 shirts at $28 --> (5000, 28)
Use the slope formula: [tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
[tex]m=\dfrac{28-32}{5000-4000}\quad =\dfrac{-4}{1000}\quad =-0.004[/tex]
Next, use the Point-Slope formula (replace x with n & replace y with p):
[tex]y-y_1=m(x-x_1)\implies p-p_1=m(n-n_1)\\\\\\p-28=-0.004(n-5000)\\\\p-28=-.004n-20\\\\\large\boxed{p=-0.004n+8}[/tex]
