Решите уравнение плиз: 5 6\7 * (2 1\4-0,25z)=0,41

56/7*(21/4-0.25z) = 0.41 
8*(21/4-1/4z) = 0.41
42-2z = 0.41
-2z = 0.41-42
-2z = -41.59
2z = 41.59
z = 41.59/2
z = 20.79