Chocolate muffins are baking in a $350-$degree oven. Let M $=$ M$($t$)$ be the temperature of the muffins t minutes after they are placed in the oven, and let D $=$ D$($t$)$ be the difference between the temperature of the oven and the temperature of the muffins. Then D satisfies Newton's law of cooling, and its equation of change is

$$

dDdt

$=0\mathrm{.}06$D$.$

$($a$)$ If the initial temperature of the muffins is the temperature of the room, $73$ degrees, find a formula for D$($t$).$

D$($t$)=$

$($b$)$ Find a formula for M$.$

M$($t$)=$

$($c$)$ The muffins will be done when they reach a temperature of $202$ degrees. When should we take the muffins out of the oven? $($Round your answer to two decimal places.$)$

min