The way(referred to to solve)the problem sounds reasonable.括号里是答案,我为了省字就没写选项,括号里是答案.请问各位精英,那个to to 是怎么回事呀?为什么两个to?直接The way referred to solve .不就行了吗?

The way(referred to to solve)the problem sounds reasonable.
括号里是答案,我为了省字就没写选项,括号里是答案.
请问各位精英,那个to to 是怎么回事呀?为什么两个to?直接The way referred to solve .不就行了吗?

原句：
The way( which/that is referred to) to solvethe problem sounds reasonable.
该句子是定语从句
( which/that is referred to)作为定语 修饰the way