$($a$)$ Let $p,q$ and $r$ be the statements $"$It is below freezing", $"$It is snowing" and "I go for skiing" respectively. Obtain the truth table for the following statement: $"$If it is snowing and not below freezing, then I go for skiing". $\%$

$($b$)$ Show that $[(pq{)}^{{?}^{?}}(qr)](pr)$ is a tautology.

$($I mark$)\%$

$($c$)$ Show that $(pq{)}^{{?}^{?}}(pr)$ and $p(q^{{?}^{?}}r)$ are logically equivalent. $\%$

$(2$ marks$)$