Let the original fraction = $$frac{x}{y}$$ $$ herefore frac{x imes 300}{y imes 250} = frac{9}{10}$$ => $$frac{x imes 6}{y imes 5} = frac{9}{10}$$ => $$frac{x}{y} = frac{9}{10} imes frac{5}{6}$$ => $$frac{x}{y} = frac{3}{4}$$