24.
а) -6a+7b+3a -4b =3b-3a=3(b-a) =3(4,2-3,2) =3*1=3.
б) 1,5x -9y -(y+1,5x)= 1,5x -9y -y-1,5x= -10y = -10*0,9 = - 9.
в) 14a-12b -a-b=13a-13b =13(a-b) = 13(2/7 -(-5/7))=13(2/7+5/7) =13*1=13.
г) 0,7y -(0,2x-0,3y)+0,2x = 0,7y -0,2x+0,3y+0,2x = y = -0,14.
25.
а) 3(2x+y)-4(2y-x) =6x+3y -8y +4x=10x-5y =5(2x-y) = 5(2*0,2 -(-2/5) )=5*(4/5)=4.
б) 7(2x/7 -3y/14) - 4(7x/2 -3y/8) =2x - 3y/2 -14x+3y/2= -12x = -12*5/6 = -10.
в) 2(4a-0,5b) -(3a-7b) = 8a -b-3a+7b=5a+6b = 5*(-0,4)+6*(1/3) = -2+2=0.
г) -6(2a/3-b/6)+4(0,75a-b/12) = - 4a+b +3a -b/3= -a +2b/3 = -(-1)+(2*3/2)/3=
1+1=2.