Create Formula for Google Sheets

On the link below you will find a Google Sheet: [login to view URL] A need a formula on columns F2, F3, F4, F5 that shows the word coincidence between the columns on the left. For example, the sentences "Hello, this is an example." and "Hello, this is an example." have a 100% word coincidence, since 5 words out of 5 are similar. However, the sentences "Hello, this is an example." and "Hello, this is an animal." have a 80% word coincidence, since 4 words out of 5 are similar. The sentences "Hello, this is an example." and "I'm not sure if that's a good example." would have a 20% coincidence, because only the word "example" coincides. Can you do it?