Life expectancy is singular, so you need to use "was" not were. Also, if the sentence refers to life expectancy (note spelling correction) in general in these countries, it doesn't need "the". So: Life expectancy in Canada and Japan was around 77. This also assumes that you are talking about life expectancy in the past. If you mean current life expectancy, you should use "is" not "was". Differences like this and whether or not to use "the" are quite subtle, and I'd need to see the sentence/s that led up to this one before being 100% certain which of them to use.

As Graham says, you should use 'was' in your example sentence. Or you could also add the word 'both', and then you can say '"were both around 77". Also you have a spelling mistake in the word 'expentancy' - it should be 'expectancy'. I would also remove the definite article - and so I would write: "Life expectancy in Canada and Japan were both around 77."

No, you should use "was".