(x-y+19)+(y-x-10)=x-y+19+y-x-10=9
1/2 = 15/30; 3/5 = 18/30; 2/3 = 20/30. 3/8 = 9/24, 5/12 = 10/24; 5/6 = 20/24.
А) (а+2b)-(4а-b)+7(b-2а)-(-b+а)=a+2b-4a+b+7b-14a+b-a=-18a+11b
б) (3х-7у)+3(у-15х)-2(у+4х)-(7х-у)=3x-7y+3y-45x-2y-8x-7x+y=-57x-5y
в) (8а-b)-(3а-5b)+(2а-7b)-(5а+2b)=8a-b-3a+5b+2a-7b-5a-2b=2a-5b
<span>г) -2(3х+5у-4)+3(2х-у+8)=-6x-10y+8+6x-3y+24=-13y+32</span>