The amount of revenue generated by a food deliveries company $($in billions of dollars$)$ can be approximated by the function

$f(x)=0\mathrm{.}772(1\mathrm{.}126{)}^x,$ where $x=1$ corresponds to the first quarter of the year $2018.$ Find the first full quarter in which the

revenue generated from food deliveries exceeded the following amounts.

$($a$)$ $$4\mathrm{.}3$ billion

$($b$)$ $$6\mathrm{.}6$ billion

$($a$)$ The first full quarter in which the revenue generated exceeded $$4\mathrm{.}3$ billion was the

$($Type a whole number.$)$

$($b$)$ The first full quarter in which the revenue generated exceeded $$6\mathrm{.}6$ billion was the

quarter of the year

$($Type a whole number.$)$

quarter of the year