noun
seven to three chances; 70% chance
Idiomatic expression for a probability split of roughly 70% vs 30%, often used in gambling, predictions, or informal estimates.
勝負は七分三分でこちらの勝ちだ。
The odds are seven to three in our favor.
彼が来る確率は七分三分と
I'd say the chances of him coming are about 70%.