Making polite suggestions; 'how about if', 'what if', 'it would be good if'.
Verb-casual, past + たら いかがですか, い-Adjective + かったら いかがですか, な-Adjective + だったら いかがですか, Noun + だったら いかがですか
Long explanation:
The ~たら いかがですか grammar point is used to make polite suggestions, ask for opinions, or imply that something would be good or desirable if the condition is met. The formation differs depending on whether it is used with a verb, い-adjective, な-adjective, or noun.