3/15 divided by 7/10

3/15 divided by 7/10  ?

$$\begin{array}{rcl} \dfrac { \frac {3}{15}} {\textcolor[rgb]{1,0,0}{\frac {7}{10} }} = \frac {3}{15}\times\textcolor[rgb]{1,0,0}{\frac {10}{7}} = \frac {3*\textcolor[rgb]{1,0,0}{10 }}{15*\textcolor[rgb]{1,0,0}{7}} = \frac {3*\textcolor[rgb]{1,0,0}{2*5 }}{3*5*\textcolor[rgb]{1,0,0}{7}} = \frac {3*\textcolor[rgb]{1,0,0}{5*2 }}{3*5*\textcolor[rgb]{1,0,0}{7}} =\frac {\textcolor[rgb]{1,0,0}{2}}{\textcolor[rgb]{1,0,0}{7}}\end{array} =0.28571428571$$