should i trade a planeswalker for a 9/9 creature in magic the gathering

my friend wants to trade his 9/9 creature for my planeswalker should i do it

What are the cards' names?

There are 17 9/9 creatures in the game, each with varying secondary market values. There are also 37 different planesalker cards, varying in prices from $2 to $150.

So in short, we need to know what cards they are.

no dont do it planeswalkers are MYTHIC RARES

You know Tibalt is a thing... He's kinda only $2.

And he's not even the cheapest mythic rare out there (Angelic Overseer goes for $1.80, while Archangel's Light and Beguiler of Wills are even cheaper at $1.30 each).

In short: Don't use rarity as a measure of how good/valuable a card is.

his Demon of Death's Gate for my Nicol Bolas, Planeswalker

You'd be getting ripped off by about 3 bucks there. Ask if he has another one or two cards to trade you along with it.

I'd say $3 isn't that big a deal, and if you're both happy with the trade then it's pretty fair.