The answer to this question would be 35
In this question, you are given multiple number names and asked to add it. To answer this question, it will be easier to split the sentences into multiple parts like this:
1. "2 tens" mean 2 * 10 =20
2. "15 ones" mean 15 * 1= 15
Then, if you add them up it will be: 20+15= 35