Assume that you borrow $27$ million JPY from some bank and

the annual interest rate is $2\mathrm{.}4\%,$

and repay monthly to pay off at just $20$ years $(=240$ months$)$

later.

$($a$)$ If you repay principal equally,

$(1)$ how much do you repay at the first time?

$($JPY$)$

$(2)$ how much is the total repayment in $20$ years $?$

$($JPY$)$

$($b$)$ If you repay principal and interest $($total$)$ equally,

$(3)$ how much do you pay every month at least $?$

$($JPY$)$

$($c$)$

$(4)$ If you will pay $160,000$ JPY principal and interest

equally, how long does it take to pay off $?$

months.