"抛硬币决定问题" can be translated into English as "flip a coin to decide the issue/matter" or "use a coin toss to make the decision".
Here are some example sentences for context:
If we can't agree, let's flip a coin to decide the issue.
（如果我们无法达成一致，那就抛硬币来决定这个问题吧。）
When in doubt, use a coin toss to make the decision.
（当拿不定主意时，就用抛硬币来做出决定吧。）