...
27 : 5 х 4 = 5,4 х 4 = 21,6.
24x-78x+54x=-13-78x+13x
24x-78x+54x+78x-13x=-13
24x+54x-13x=13
65x=13
x=13/65
x= 1/5
Х - (-11) = 11
х + 11 = 11
х = 11 - 11
х = 0
3) ab + ac + am + yc + yb + ym =
= (ab + ac + am) + (yc + yb + ym) =
= a(b + c + m) + y(c + b + m) = (a + y)(c + b + m)
4) kp - kc - px + cx + c - p =
= (kp - kc) - (px - cx) - (p - c) =
= k(p - c) - x(p - c) - (p - c) =
= (k - x - 1)(p - c)