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;...

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