You want to build a capital of $30,000$ in $5$ years by means of

payments into an account, which yields an EAIR of $9\%,$ for the

first $2$ years, $8\%$ for the following $2$ years and $7\%$ for the last one.

Determine the value of the payments in the following cases:

a$.$ The Payments are at the end of each month.

b$.$ The payments are at the beginning of every semester.