An arithmetic sequence is a sequence of numbers a_{1}, a_{2}, a_{3},... where a_{n} - a_{n-1} has the same value for every n. For example, 2, 4, 6, 8, 10,....is such a sequence where the difference between any 2 consecutive numbers is 2. Given, a, b, c, d, and e are consecutive numbers in such a sequence and a + b + c + d + e = 90. What is the value of c?

Erin remembers that her mother's birthday is after 18^{th} but before 23^{rd} of February. Her sister Ammaarah remembers that her mother's birthday is before 27^{th} and after 21^{st} of February. On which date of February is their mother's birthday?