Pls explain how to do this

Answer:
3 1/12 miles
Step-by-step explanation:
[tex]6\frac{3}{4} -3\frac{2}{3} \\\\=\frac{27}{4} -\frac{11}{3}\\\\ =\frac{81}{12} -\frac{44}{12} \\\\=\frac{37}{12}\\\\=3\frac{1}{12}[/tex]
Make them into mixed fractions and then find the least common denominator (12). solve.