what is the answer and how?

Answer:
[tex]\large\boxed{4\dfrac{5}{6}-\dfrac{17}{18}=3\dfrac{8}{9}}[/tex]
Step-by-step explanation:
[tex]4\dfrac{5}{6}-\dfrac{17}{18}\\\\\text{Find the common denominator.}\\\text{The common denominator is 18}=6\cdot3\\\\4\dfrac{5}{6}=4\dfrac{5\cdot3}{6\cdot3}=4\dfrac{15}{18}\\\\4\dfrac{5}{6}-\dfrac{17}{18}=4\dfrac{15}{18}-\dfrac{17}{18}=4+\dfrac{15}{18}-\dfrac{17}{18}=4-\dfrac{2}{18}=3\dfrac{18}{18}-\dfrac{2}{18}=3\dfrac{16}{18}\\\\=3\dfrac{16:2}{18:2}=3\dfrac{8}{9}[/tex]