I need help with the last two, the ones in blank

The political pollster Canter is preparing for a national election. It would like to poll at least 1,800 Democrats and 1,800 Republicans. Each mailing to the East Coast gets responses from 100 Democrats and 50 Republicans. Each mailing to the Midwest gets responses from 100 Democrats and 100 Republicans. Each mailing to the West Coast gets responses from 50 Democrats and 100 Republicans. Mailings to the East Coast cost $40 each to produce and mail, mailings to the Midwest cost $60 each, and mailings to the West Coast cost $50 each. How many mailings should Canter send to each area of the country to get the responses it needs at the least possible cost? (East Coast, Midwest, West Coast) = ( 12,0,12 ) What is the lowest possible cost? $ 1080 What are the shadow costs of a Democratic response and of a Republican response? per Democrat per Republican The political pollster Canter is preparing for a national election. It would like to poll at least 1,800 Democrats and 1,800 Republicans. Each mailing to the East Coast gets responses from 100 Democrats and 50 Republicans. Each mailing to the Midwest gets responses from 100 Democrats and 100 Republicans. Each mailing to the West Coast gets responses from 50 Democrats and 100 Republicans. Mailings to the East Coast cost $40 each to produce and mail, mailings to the Midwest cost $60 each, and mailings to the West Coast cost $50 each. How many mailings should Canter send to each area of the country to get the responses it needs at the least possible cost? (East Coast, Midwest, West Coast) = ( 12,0,12 ) What is the lowest possible cost? $ 1080 What are the shadow costs of a Democratic response and of a Republican response? per Democrat per Republican