2*2/5 (5/6-4x) = 1*1/5

2 * 2/5 * (5/6 - 4x) = 1 * 1/5

4/5 * (5/6 - 4x) = 1/5

5/6 - 4x = 1/5 : 4/5

5/6 - 4x = 1/5 * 5/4

5/6 - 4x = 5/5 * 1/4

5/6 - 4x = 1 * 1/4

5/6 - 4x = 1/4

4x = 5/6 - 1/4

4x = 10/12 - 3/12

4x = (10 - 3) / 12

4x = 7/12

x = 7/12 : 4

x = 7 / (12 * 4)

x = 7/48

Ответ 7/48