171.
1) (2/3 ) / (4/9*x - 4/9) +1/20 =4/5 ;
(2/3)* 9 / (4/9*x - 4/9)*9 = 4/5 -1/20;
2*3 / (4x -4) = 15 / 20 ;
2*3/ 4(x -1) = 3/4 ;
3/ 2(x -1) = 3/4 ;
2(x - 1) =4 ;
x-1 =2 ;
x=3.
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171.
2) (5/7) / (6/7 *x + 3/7) - 1/2=1/6 ;
(5/7) *7 / ( (6/7 *x + 3/7)*7 ) =1/6 +1/2 ;
5/ (6x +3) =4 /6 ;
5/ (3(2x +1) ) =2 / 3 ;
3(2x +1) =5 : 2/3 ;
3(2x+1) =15 /2
2x+1 = 15/2 : 3 ;
2x+1 = 5/2 ;
2x=5/2 -1 ;
2x =3/2 ;
x =3/4 .
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(5/7) / (6/7 *x + 3/7) - 1/2=1/6 ;
5 / (6x+3) = 1/2+1/6 ;
5/(3(2x+1) ) = 2/3 ;
5/(2x+1 ) = 2 ;
2x+1 = 5 / 2 ;
2x =5/2 -1
2x =3/2 ;
x =3/4