7*3/4 (-2,4 а+16/31b-2) - 11*1/5 (-1,5a+5/7b-0,5)

7*3/4 (-2,4 а+16/31b-2) - 11*1/5 (-1,5a+5/7b-0,5) = 7 * (-1,8 а) + 12/31b-1,5-11 * (-0,3a) + 1/7b-0,1 = - 12,6a+12/31b-1,5+3,3a+1/7b-0,1 = - 9,3a+115/217b-1,6

3/4 * (-2,4) = 3/4*24/10=72/40=9/5=1,8

3/4*16/31=48/124=12/31

3/4*2=6/4=3/2=1,5

1/5*1,5=1/5*15/10=15/50=3/10=0,3

1/5*5/7=5/35=1/7

1/5*0,5=1/5*5/10=5/50=1/10=0,1

7*1.8=7*18/10=126/10=12,6

11*0,3=11*3/10=33/10=3,3

-12,6+3,3=-9,3

12/31+1/7=84/217+31/217=115/217

-1,5-0,1=-1,6