Решите устранение. 9/10у=4 1/2; (1-7/10)х=2 1/4; (1/4+1/5)х=1 4/5; (3 1/8+1 3/4)х=2 1/6; (2 1/12-1 5/6)х=3/4;

1) $frac{9}{10} y=4 frac{1}{2}$
$frac{9}{10}y= frac{9}{2}$
$y= frac{9}{2} : frac{9}{10} = frac{9}{2} * frac{10}{9} =5$
y=5
2) $(1- frac{7}{10} )x=2 frac{1}{4}$
$1- frac{7}{10} = frac{3}{10}$
$frac{3}{10}x = frac{9}{4}$
$x= frac{9}{4} : frac{3}{10}= frac{9}{4} * frac{10}{3}= frac{15}{2}$
y=7.5
3) ( $( frac{1}{4} + frac{1}{5} )x=1 frac{4}{5}$
$frac{1}{4} + frac{1}{5} = frac{1*5}{4*5} + frac{1*4}{5*4} = frac{5}{20} + frac{4}{20} = frac{9}{20}$
$frac{9}{20} x=1 frac{4}{5}$
$frac{9}{20} x= frac{9}{5}$
$x= frac{9}{5} : frac{9}{20} = frac{9}{5} * frac{20}{9} =4$
y=4