Уравнение
4/15y=2/5
7/8y=14
9/10y=4 1/2

$1)frac{4}{15} y = frac{2}{5} * frac{15}{4}= frac{30}{20} = frac{3}{2} =1,5y = frac{2}{5}$
$2) frac{7}{8} y = 14$
$y = 14*frac{8}{7}=2*8=16$
$3) frac{9}{10} y = 4 frac{1}{2}$
$frac{9}{10} y = frac{9}{2}$
$y = frac{9}{2} * frac{10}{9}= frac{10}{2} = 5$