Уравнение: 9:(4/5-5/4)/ 7:(3/4-4/3)=x/5:(3/2-2/3)

9 : (4/5 - 5/4)/7 : (3/4 - 4/3) = x/5 : (3/2 - 2/3);

9 : ((4 * 4 - 5 * 5)/20)/7 : ((3 * 3 - 4 * 4)/12) = x/5 : ((3 * 3 - 2 * 2)/6);

9 : ((16 - 25)/20)/7 : ((9 - 16)/12) = x/5 : ((9 - 4)/6);

9 : (- 9/20)/7 : (- 7/12) = x/5 : (5/6);

9 * (- 20/9)/7 * (- 12/7) = x/5 * 6/5;

- 20/(- 12) = x/5 * 6/5;

20/12 = (x * 6)/(5 * 5);

20/12 = (x * 6)/(5 * 5);

20/12 = (6 * x)/25;

(4 * 5)/(4 * 3) = (6 * x)/25;

5/3 = (6 * x)/25;

5 * 25 = 3 * (6 * x);

125 = 18 * x;

x = 125 : 18;

x = 6 17/18.

Ответ: 6 17/18.