If a polygon has $44$ diagonals,then the number of its sides is:

$A$ polygon has $54$ diagonals. Then,the number of its sides is

$A$ polygon has $35$ diagonals,then the number of its sides is

Let $t_n$ denote the number of integral-sided triangles with distinct sides chosen from $\{1, 2, 3, \ldots, n\}$. Then,$t_{20} - t_{19}$ equals

Five boys and three girls are seated in a row at random. What is the probability that all three girls sit together?

Three of the six vertices of a regular hexagon are chosen at random. The probability that the triangle formed by these three vertices is equilateral is equal to