Ответ:

-1,4x(-6y) = 8,4xy.

19m + 5p - 11m - 2p = (19m - 11m) + (5p - 2p) = 8m + 3p.

k(25 - k) + (k + 12) = 25k - k^2 + k + 12 = -k^2 + 26k + 12.

-4 - (3 + a) + 2(a - 7) = -4 - 3 - a + 2a - 14 = a - 19.