1.
а) 4*(5-y)-30 = 20-4y-30 = -10-4y = -2(5+2y)
б) -8*(9+x)+50 = -72-8x+50 = -22-8x = -2(11+4x)
в) -12*(-a-2)-10 = 12a+24-10 = 12a-14 = 2(6a-7)
2.
a) -(7-x)+(3x-14) = -7+x+3x-14 = -21+4x
b) (21-a)-(20-2a) = 21-a-20+2a = 1+a
3.
(0,34-2,59)*7,8 + 2,9*(-4,31-0,79) = (-2,25 * 7,8)+(2,9 * (-5,1)) = -17,55 + (-14,79) = -32,34