Упростите выражение: 5/7(2,8c-4 1/5d)-2,4(5/6c-1,5d)

5/7(2,8с- 4 1/5d)-2,4(5/6c-1,5d) = 5/7(28/10*c -21/5*d) - 24/10(5/6*c-3/2*d) = (140c/70 - 21/5*d) - (120c/60-72d/20) = 2c-21/5*d - 2c +18/5*c = - 3/5*d = -0,6d