(how much) do you want to bet? idiom informal
（表示确定对方错了）你敢打赌吗？你想赌多少？
said in answer to something that someone has said, meaning that you are certain that they are wrong
"Surely she won't be late this time." "How much do you want to bet?" “她这次肯定不会迟到。”“那你敢跟我赌多少？”