Write a formula for the price $p$ of a gallon of gas in $t$ is $$4\mathrm{.}30$ on day $t=0$ and the price is:

$($a$)$ Increasing by $$\mathrm{.}51$ per day.

$p(t)=$

$($b$)$ Decreasing by $$\mathrm{.}61$ per day.

$p(t)=$

$($c$)$ Increasing by $3\%$ per day.

$p(t)=$