$\mathop 2\nolimits^x = 3,{{\mathop 4\nolimits^{9 + 7x} } \over {\mathop {64}\nolimits^{3 + 2x} }} = {{\mathop {(\mathop 2\nolimits^2 )}\nolimits^{9 + 7x} } \over {\mathop {(\mathop 2\nolimits^6 )}\nolimits^{3 + 2x} }} = {{\mathop 2\nolimits^{`18 + 14x} } \over {\mathop 2\nolimits^{`18 + 12x} }} = {{\mathop 2\nolimits^{18} \times \mathop 2\nolimits^{14x} } \over {\mathop 2\nolimits^{18} \times \mathop 2\nolimits^{12x} }} = \mathop 2\nolimits^{2x} = \mathop {(\mathop 2\nolimits^x )}\nolimits^2 = \mathop 3\nolimits^2 = 9$