First month's profit of the company = $2,400.
After the first month, the profit is modeled by the function
J(t) = 2.5t + 1,250, t is the number of months after the first month the shop opened.
Now, P(t) describes the total profit earned by the company.
So, P(t) = (Profit earned from first month) + (Profit earned from remaining 11 months of the year)
= 2400 + (2.5t + 1250)
= 2.5t + 3650
Hence, total profit earned for the year = 2.5t + 3650.