My old electric cooktop and a separate wall oven were attached together to a single range cord connected to a 40 amp outlet ; is this OK? If it is not how can I do it?

You should have each on a separate cord. You need to know the minimum ampacity of each appliance. It may be possible to have a breaker box supplied from the 40 amp circuit and two receptacles run off this box, or two lines straight to the oven and cook-top if the box is accessible in the same room. Without knowing the minimum ampacity there is no way to know the correct path to take.

Is a 40 amp breaker and is only one line;the appliances are 30 amp each.Please help

Easier to find an old post, than code:

https://www.askmehelpdesk.com/electrical-lighting/separate-cooktop-wall-oven-same-circuit-259295.html