3,5×(х+2 1/4) =14, (1 3/4 +х)÷1,9=2,5; (7,1-х)÷3,6=1 1/2

№1

3,5 * (х + 2 1/4) = 14;

х + 2 1/4 = 14 : 3,5;

х + 2 1/4 = 4;

х = 4 - 2 1/4;

х = 4 - 9/4;

х = 16/4 - 9/4;

х = 7/4 = 1 3/4.

Ответ: х = 7/4 = 1 3/4.

№2

(1 3/4 + х) : 1,9 = 2,5;

1 3/4 + х = 2,5 * 1,9;

1 3/4 + х = 4,75;

х = 4,75 - 1 3/4;

х = 475/100 - 7/4;

х = 475/100 - 175/100;

х = 300/100 = 3.

Ответ: х = 300/100 = 3.

№3

(7,1 - х) : 3,6 = 1 1/2;

7,1 - х = 1 1/2 * 3,6;

7,1 - х = 3/2 * 36/10;

7,1 - х = 25/7;

х = 7,1 - 27/5;

х = 71/10 - 27/5;

х = 71/10 - 54/10;

х = 17/10 = 7/10.

Ответ: х = 17/10 = 7/10.