Answer:
[tex]4\frac{1}{2}[/tex] or 4.5 hours
Step-by-step explanation:
Total length of playlist = [tex]6\frac{3}{4} = \dfrac{27}{4}[/tex] hours
Time spent cleaning/listening = [tex]\frac{2}{3}[/tex] of total length of playlist
= [tex]\dfrac{2}{3} \times \dfrac{27}{4} = \dfrac{9}{2}[/tex] hours = [tex]4\frac{1}{2}[/tex] hours