3_7 *(3-5x)-4_5*(x-3_5)=0

3/7 * (3 - 5 * x) - 4/5 * (x - 3/5) = 0; 

Решим уравнение и найдем его корешки.  

3/7 * 35 * (3 - 5 * x) - 4/5 * 35 * (x - 3/5) = 0;  

3 * 5 * (3 - 5 * x) - 4 * 7 * (x - 3/5) = 0;  

15 * (3 - 5 * x) - 28 * (x - 3/5) = 0; 

15 * 3 - 15 * 5 * x - 28 * x + 28 * 3/5 = 0; 

45 - 75 * x - 28 * x + 28 * 3/5 = 0; 

45 - 103 * x + 28 * 3/5 = 0;  

45 * 5 - 103 * x * 5 + 28 * 3 = 0; 

225 - 515 * x + 84 = 0; 

309 - 515 * x = 0; 

309 = 515 * x; 

515 * x = 309; 

x = 309/515; 

Ответ: х = 309/515.