ответ: A.
Пошаговое объяснение:
1. (1/2)+(5/6)-(7/9)=(1*9+3*5-2*7)/18=(9+15-14)/18=10/18=5/9.
2. (5/9)::1²/₃=(5/9):(5/3)=5*3/(9*5)=1/3.
3. 15:2,4-6¹/₃₆=15:2²/₅-6¹/₃₆=(15:(12/5))-217/36=(15*5/12)-(217/36)=
=(75/12)-(217/36)=(75*3-217)/36=(225-217)/36=8/36=2/9.
4. (1/3)/(2/9)=1*9/(3*2)=9/6=1,5.
5. 2,75-(2/3)=2³/₄-(2/3)=(11/4)-(2/3)=(11*3-2*4)/12=(33-8)/12=25/12.
6. (25/12)*1.2=(25/12)*1¹/₅=(25/12)*(6/5)=25*6/(12*5)=2,5.
7. (7/30)+(5/12)=(7*2+5*5)/60=(14+25)/60=39/60.
8. (39/60):0,13=(13/20):(13/100)=13*100/(13*20)=5.
9. 2,5/5= 0,5.
10. 1,5+0,5=2.
11. 2:0,125=2:(1/8)=2*8=16.
-3x-2x+8x=-18-8+16
3x=-10
x=-10\3.это.дробь