Выражение : 1) 0,3(1,2x-0,5y)-1,5(0,4x-y) 2) -2,4(2,5a-1,5b)+0,5(1,8b+5,6a) 3) -1,8(3,5m-5)-6,5(0,8-0,4m) 4) 4/9 (1 1/2c - 3/8) - ( 1 5/6 - 1 1/3c) 5) 1,2 (5/6k + 0,4n) - 1,8 (5/9k - 0,3n) 6) (1/6 a + 6,5) - ( 2 7/9a + 3 1/3) 7) 3/7 ( 0,56x - 4,9y) - 6/13 ( 0,52x - 3,9y) 8) 6 ( 1/4 k - 5/6) - 15 ( 0,6 - 2 1/3k)

1) 0,3(1,2x-0,5y)-1,5(0,4x-y)=0,36x-0,15y-0,6x+1,5y=0,3y+1,35 2) -2,4(2,5a-1,5b)+0,5(1,8b+5,6a)=-6a+3,6b+0,9b+2,8a=-3,2a+4,5b 3) -1,8(3,5m-5)-6,5(0,8-0,4m)=-6,3m+9-5,2+2,6m=-3,7m+3,8 4) 4/9 (1.1/2c - 3/8) - ( 1.5/6 - 1.1/3c)=4/9 (3/2c - 3/8) - (11/6 - 4/3c) =

4/9 (12/8c - 3/8) - (11/6 - 8/6c)= 4/9 (9/8c  - 3/6c)=4/9 (9/8c  - 4/8c)=4/9*5/8c = 5/18c 5) 1,2(5/6k + 0,4n) - 1,8(5/9k - 0,3n)=6/5 (5/6k +2/5n) - 9/5(5/9k - 3/10n)=

k +12/25n -k+27/50n=    24/50n+27/50n=51/50n=1.1/50 n 6) (1/6 a + 6,5) - ( 2 7/9a + 3 1/3)=1/6 a + 13/2 - 25/9a  - 10/3=

3/18 a + 39/6 - 50/18a  - 20/6 =-47/18a+19/6=-2.11/18a+3.1/6 7) 3/7(0,56x - 4,9y) - 6/13( 0,52x - 3,9y)=

3/7(56/100x - 49/10y) - 6/13(52/100x - 39/10y)=

=0,38x-2,1y-0,24x+1,8y=0,14x-0,3y

tg = 1\cos

2. cos = 1\2

0. cos = 0

надеюсь, что не ошибся)