1) (x+20)*45 =3 105 2) x:34 = 17 000 + 204 3) 57*(500 - x) = 11 457
45x+900 = 3 105 x:34 = 17 204 57*500 = 28 500
45x = 3 105 - 900 x = 17 204 * 34 28 500-57x = 11 457
45x = 2 205 x = 584 936 28 500-11 457 = 17 043
x = 49 57x = 17 043
x = 17 043 : 57
x = 299
4) 16 912 : x = 7 890 - 7 834
7 890 - 7 834 = 56
16 912 : x = 56
x = 16 912 : 56
x = 302