Which one is more important in losing weight and being healthy - diet or exercise?

Which one would be more important, or are they both equal?

Someone told me that it is 80% diet and 20% exercise in order to lose weight and/or be healthy.

Another person told me you can eat healthy as much and as long as you’d like, but if you don’t exercise you can’t lose weight.

Or is it 50/50 diet and exercise?

What do you guys think?