I am a novice of R. Thanks for your help in advance.

I newly created the new data frame by joinning 3 data frames as in the image below.
[![enter image description here](https://i.stack.imgur.com/ZrGQ1.png)](https://i.stack.imgur.com/ZrGQ1.png)

After merging the dfs, I tried to rename the column names to get the values for over 70's. But there are still 3 different column names as below.

How can I merging the values for 70 and over 70's?

[![enter image description here](https://i.stack.imgur.com/NIYfE.png)](https://i.stack.imgur.com/NIYfE.png)