Which expression is equivalent to

2/3(9x-6)+4(1/2 x -- 1/2)


a:2/3(6x-9)+1/6(x+12)
b:2/3(3x-6)+1/6(x-12)
c:3/4(4x-8)+5(x+15)
d:3/4(4x-12)+1/6(30x+18)