chasis problem???

[nissan240s_x]

there is some rust on the frame so im not sure if this is a big problem, b/c wen i first got my '89 240sx it was not running and sat around for a year. is this a tough fix and possibly cost me a lot of $$$ to hav fixed b/c i was told that my car may not even b street legal anymore and if it went through inspection it would fail...