return to investors of $$19,000.$ Each month, he must recruit enough new investors to increase the return by $4\%.$

$($a$)$ Find a formula that gives the return $R,$ in dollars, that the operator must pay after $t$ months.

$R(t)=$

$($b$)$ How much must the operator pay to investors at the end of $3$ years? $($Round your answer to two decimal places.$)$

$

number of new investors.$)$

x new investors