Sets Questions

In a class of $80$ students, $45$ play cricket, $35$ play football, and $15$ play both cricket and football. How many students play only cricket?

The following Venn diagram shows the result of a survey of $1500$ persons in a city with respect to their knowledge of Kannada (K), Hindi (H) and Telugu (T). Let the exclusive single language regions be represented by the values: $300$ (for Kannada only), $500$ (for Hindi only), and $250$ (for Telugu only).
How many people know only one language?

The following Venn diagram shows the result of a survey of $1500$ persons in a city with respect to their knowledge of Kannada (K), Hindi (H) and Telugu (T). The number in the central overlapping region where all three circles intersect is $50$.
How many people know all the three languages?

The following Venn diagram shows the result of a survey of $1500$ persons in a city with respect to their knowledge of Kannada (K), Hindi (H) and Telugu (T).
Let the intersection regions between exactly two sets be represented by the values: $150$ (for K and H only), $100$ (for H and T only), and $200$ (for K and T only).

How many people know exactly two languages?