To find the number of students who play only Chess, we can use the principle of set theory.
Let's denote:
- \( C \): the number of students who play Carom
- \( H \): the number of students who play Chess
- \( B \): the number of students who play both games
From the given data:
- \( C = 400 \) (students who play Carom)
- \( H = 150 \) (students who play Chess)
- \( B = 130 \) (students who play both games)
We want to find the number of students who play only Chess. This can be calculated using the following formula:
\[ \text{Students who play only Chess} = H - B \]
Substituting the values:
\[ \text{Students who play only Chess} = 150 - 130 = 20 \]
Therefore, the number of students who play only Chess is 20.