To go on a summer trip, Dan borrows $$200.$ He makes no payments until the end of $6$ years, when he pays off the entire loan. The lender charges simple interest at an annual rate of $6\%.$

Answer the following questions. If necessary, refer to the list of financial formulas.

$($a$)$ How much total interest will Dan have to pay?

$($b$)$ What will the total repayment amount be $($including interest$)?$

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