Answer: Celeb felt calm because he knows the solution to his problem .
Explanation: This sentence should be written in either of these two ways: "Celeb felt calm because he knew the solution to his problem", or "Celeb feels calm because he knows the solution to his problem."
- This is because "felt" is past tense, and "knows" is present tense. Both of these words need to be either present or past tense for a grammatically correct sentence.
