To find the miles for 3rd day, we take away the miles she biked for the first two day from the total.
[tex]50 - 17 \dfrac{7}{8} - 18\dfrac{5}{7} [/tex]
[tex]=50 - 17 \dfrac{7 \times 7}{8 \times 7} - 18\dfrac{5 \times 8}{7 \times 8} [/tex]
[tex]= 48 \dfrac{112}{56} - 17 \dfrac{49}{56} - 18\dfrac{40}{56} [/tex]
[tex]= 13 \dfrac{23}{56} \text { miles }[/tex]
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Answer: She traveled 13 23/56 miles on the third day.
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