A$.$ Given the following $2-$period binomial tree, find the value of a call with a strike price of $21.$ The risk$-$free rate $=4\%$ and t $=0\mathrm{.}1.$

$25$

$22$

$2019$

$18$

$16$

B$.$ Assume that the value of the call is $$2\mathrm{.}00.$ Use the data provided after figuring out step one and put$-$call parity to find the put premium. $($The put and call have identical strikes and identical expiration dates$).$