I'd like to propose an alternative plan. There are two ways to do it.
I have plan B and there are two ways of doing it.
ご質問ありがとうございます。
① "I'd like to propose an alternative plan."=「代替案を提案したいです。」
"That are two ways to do it."=「2つの方法があります。」
② "I have plan B and there are two ways of doing it."=「代替案があり、それをするには2つ方法があります。」
ご参考に。