Given the following information for $3$ risky assets:

$($a$)$ Suppose the risk$-$free rate is $4,$ find the tangency portfolio for these $3$ risky assets, assuming

short$-$selling is allowed.

$($b$)$ Repeat part $($a$)$ assuming short$-$selling is not allowed.

$($c$)$ Write down the capital allocation line $($CAL$)$ equation for the tangency portfolio in part

$($a$).$