x+1/9=1/8
x =1/8 -1/9 =1/ 72
x-2/3=4/5
x = 2/3 +4/5 = ( 10+12) /15= 22/15
5/6-x=7/9
x = 5/6- 7/9= (15- 14)/ 18 = 1/ 18
7/4+x=4
x = 4 - 7/4 = (16-7) /4=9 / 4