A new department store is planning a massive advertisement campaign during the Memorial day week. They are considering 4 different advertising channels: TV, Radio, Newspaper, and Online. Each of these channels differ in the cost per ad, the number of impressions per ad (the number of people who viewed/listened to the ad), and the number of visits (either to the website or the physical store) from people of different age groups.

Everyday in that week, the store wants to achieve at least 500 total impressions, at least 60 visits from people in the above 60 age group, at least 100 visits from people in the 26-60 age group, and at least 80 visits from people in the 25 and below age group.

Formulate a linear programming problem to help the store decide how many ads for each channel to buy everyday of that week to satisfy the goal. Please use Python's pulp package to find the optimal solution of the LP.

Channel TV Radio Newspaper Online Cost per ad Impressions per ad Visits from age group 60+ Visits from age group 26-60 Visits from age group 0-25 $5000 400 30 20 20 $2000 200 20 20 40 $3000 150 0 40 10 $8000 500 0 40 50