The first row of an open-air theatre has 20 seats and each succeeding row has 2 more seats than the previous one. The management wants to reserve a consecutive set of rows starting with the kth row and ending with the mth row (where m>k) such that:
a. Part 1: (i) the total number of seats in these reserved rows is 420,
b. Part 2: (ii) the last of the reserved rows has exactly 15 more seats than the first reserved row.
c. Part 3: Find the values of k and m, and state the number of seats in each of the reserved rows.