0.6y : 9 = 1.3-y : 4.5

Найдем корень уравнения.

(0.6 * y)/9 = (1.3 y)/4.5;

Упростим уравнение.

(6/10 * y)/9 = (1.3 y)/(9/2);

(3/5 * y)/9 = (1.3 y)/(9/2);

3 * y/5 * 1/9 = (1.3 y)/1 * 2/9;

3 * y/5 = (1.3 y) * 2; 

3 * y = 5 * 2 * (1.3 y);

Раскроем скобки.

3  * y = 10 * (1.3 y);

3 * y = 10 * 1.3 10 * y;

3 * y = 13 10 * y;

3 * y + 10 * y = 13;

y * (3 + 10) = 13;

y * 13 = 13;

13 * y = 13;

y = 13/13;

y = 1.