[tex] \dfrac{2^{-1} + 5^{-1}}{10^{-1} - 5^{-2}} = [/tex]
[tex] = \dfrac{\frac{1}{2} + \frac{1}{5}}{\frac{1}{10} - \frac{1}{5^2}}[/tex]
[tex] =\dfrac{\frac{1}{2} + \frac{1}{5}}{\frac{1}{10} - \frac{1}{25}}[/tex]
[tex] =\dfrac{\frac{5}{10} + \frac{2}{10}}{\frac{5}{50} - \frac{2}{50}}[/tex]
[tex] =\dfrac{\frac{7}{10}}{\frac{3}{50}}[/tex]
[tex] = \frac{7}{10} \times \frac{50}{3} [/tex]
[tex] = \frac{7}{1} \times \frac{5}{3} [/tex]
[tex] = \frac{35}{3} [/tex]
