a. 7/12 - 1/4 : ( -4/11 - x ) = 125%
=> 1/4 : ( -4/11 - x ) = 7/12 - 5/4 = -2/3
=> -4/11 - x = 1/4 : -2/3
=> -4/11 - x = -3/8
=> x = -4/11 - ( -3/8 )
=> x = 1/88
b. 1/2x - 1/3 = 2/3x - 5/6
=> 1/2x - 2/3x = 1/3 - 5/6
=> -1/6x = -1/2
=> x = -1/2 : -1/6
=> x = 3