Question

Решить ур-е 5*(3-2y)-4*(9-y)=3*(y+5)-21

Answer 1

$5(3-2y)-4(9-y)=3(y+5)-21$

 

$15-10y-36+4y=3y+15-21$

 

$15-10y-36+4y-3y-15+21=0$

 

$(15-36-15+21)+(-10y+4y-3y)=0$

 

$-15-9y=0$

 

$9y=-15$

 

$y=-15:9$

 

$y=-\frac{15}{9}=-\frac{5}{3}=-1\frac{2}{3}$