I don't know about the first one but for the second one:
[tex] {2}^{3x + 2} - {2}^{3x} = 48 \\ \Leftrightarrow {2}^{3x} {2}^{2} - {2}^{3x} = 48 \\ \Leftrightarrow {2}^{3x} ( 4 - 1) = 48 \\ \Leftrightarrow 3 \times {2}^{3x} = 48 \\ \Leftrightarrow {2}^{3x} = 16 \\ \Leftrightarrow {2}^{3x} = {2}^{4} \\ \Leftrightarrow 3x = 4\Leftrightarrow x = \frac{4}{3} [/tex]
