Problem $(3)$:

For the circuit shown,

$($a$)$ Using Source Transformation method, find the Thevenin equivalent circuit to the left of the terminals a$-$b$.$

$($b$)$ Using Mesh$-$Current Method, find the Thevenin equivalent circuit to the left of the terminals a$-$b$.$

$($c$)$ Find the current through $R_L=6,16,$ and $36.$

$($d$)$ Finally, calculate the maximum power that can be delivered to $R_L$