What's the function of this と

Question

これを青いのと取り替えてください。 I can't figure how this と (〜のと) works here

Answer 1

「これを青{あお}いのと取{と}り替{か}えてください。」

First of all, 「青いの」 means "a blue one".

「A + を + B + と or に + 取り替える」

means:

"to exchange A for B"

So, in this case, the と or に functions as the "for" in the English equivalent. You have no choice but to use it to make it grammatical.

"Please exchange this for a blue one."