20x-19
---------- = 20
20-19x
20x + 19x = 19 + 20 · 20
39x = 419
x = 419 / 39 Либо x = 10.74
1/2(2х+1)=3;
1х+1/2=3;
1х=3-1/2;
1х=2,5;
х=2,5:1;
х=2,5.
Ответ:2,5.