Answer
$c=\frac{Q}{w(T_1-T_2)}$
Work Step by Step
To solve the given equation for $c$, we divide both sides by $w(T_1-T_2)$
$$
Q=wc(T_1-T_2)\Longrightarrow \frac{Q}{w(T_1-T_2)}=\frac{wc(T_1-T_2)}{w(T_1-T_2)}\\
\Longrightarrow c=\frac{Q}{w(T_1-T_2)}
.$$
