9/10 divided by (1/10 plus 2/5)

[tex]\boxed{ \frac{ \frac{9}{10} }{( \frac{1}{10} + \frac{2}{5} )} = \frac{ \frac{9}{10} }{ \frac{1}{2} } = \frac{9}{10} . \frac{2}{1} = \frac{18^{\div2}}{10^{\div2}} ~\to~\boxed{ \frac{9}{5}} }[/tex]

1.8 is the answer1/10+2/5 is equal to 0.5That divided by 9/10 is 1.8 or 1 8/10