(1 3/4+х): 1,9=2,5 (7,1-х): 3: 6=1 1/2

(1 3/4+ Х):1,9=2,5;
(1,75+Х)= 2,5• 1,9;
Х= 4,75 -1,75;
Х= 3;
Проверка;
(1 3/4+ 3): 1,9= 2,5
(1,75+3):1,9=2,5;
4,75:1,9=2,5;
2,5=2,5;

(7,1-Х):3,6=1 1/2;
(7,1-Х)= 1,5• 3,6;
7,1-Х= 5,4;
Х= 7,1-5,4;
Х= 1,7;
Проверка;
(7,1- 1,7): 3,6= 1 1/2;
5,4:3,6= 1,5;
1,5= 1,5;