Answer:
Hosting a party of this magnitude requires cleaning and organizing the house before you get to the part where you can add decorations to the room
Explanation:
Infinitives are those verbs that are without an inflection and will always begin with "to". Gerunds, on the other hand, are those nouns that are derived from verbs. Though they are verbs, they function as nouns, with the addition of "-ing" in their words. Gerunds always end in "-ing". So, the given sentence
"<em>To host a party of this magnitude requires to clean and to organize the house before you get to the part where you can add decorations to the rooms</em>"
will be changed into
"<u><em>Hosting</em></u><em> a party of this magnitude requires </em><u><em>cleaning</em></u><em> and </em><u><em>organizing </em></u><em>the house before you get to the part where you can add decorations to the room</em>".