We start with -5=log_2x. Now, we can rewrite a logarithm as an exponentiation equation, like this: color(red)(y)=color(blue)(b)^(color(green)(x) becomes log_color(blue)(b)color(red)(y)=color(green)(x) and vice versa. So, log_color(blue)(2)color(red)(x)=color(green)(-5) becomes color(red)(x)=color(blue)(2)^(color(green)(-5).