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(not) so; (not) particularly; (not) very; (not) that much
左程気にすることではないと思います。
It's nothing to worry so much about.
左程高くないので買いやすい価格です。
It's not so expensive, so it's easy to buy.
両者に左程の差はないと感じました。
I felt there wasn't much difference between the two.