Answer:
[tex]143\ oil\ changes[/tex]
Step-by-step explanation:
we know that
Frances can complete [tex]91[/tex] oil changes in [tex]7[/tex] days
so
by proportion
Find how many oil changes complete in [tex]11[/tex] days
[tex]\frac{91}{7}\frac{oil\ changes}{days} =\frac{x}{11}\frac{oil\ changes}{days}\\ \\x=11*91/7\\ \\x=143\ oil\ changes[/tex]