[embee]

Hmmm..........tricky.

In sentiment then Lozzo and the Squid are indubitably correct. However the rear sprocket looks pretty decent in the pic, and the chain is at least gooey rather than red rust, and if it's still decent and funds are not overflowing then YC has the vote from me, a new front sprocket will set you back, what, a tenner, and for that you'll probably extend the remaining life of the chain significantly I'd wager. It's your call, but just a new front isn't the wrong thing to do IMO if the chain condition justifies it.

If you can lift the chain off the rear sprocket enough to slip a bacon buttie through then renew the set.