問い合わせる
といあわせる · toiawaseru · JLPT N1 · verb-ichidan
to inquire
問い (question) + 合わせる (match up): match your question with someone who has the answer
問い means question and 合わせる means to join or match up. To 問い合わせる is to join your question to a source that can answer it.
合 — 乛 (lid/roof) + 口 (mouth)
Originally a pictograph of a lidded vessel — a cover (亼) closing over an opening (口) — giving the core sense of 'come together, join, fit.' From 'fit/match' it extended to 'combine, unite, agree' and to measure-word uses. The reading hé reflects this 'joining' meaning.