S = { all integers x:10 less than or equal to x less than or equal 30}

The set S is the set of all integers x such that 10 ≤ x ≤ 30. This includes all integers from 10 to 30, inclusive. So, $$ S=\left\lbrace10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\right\rbrace $$