Answer:

-1/2

Step-by-step explanation:

let the value be x

therefore,

-2/3 - x = -1/6

-x= 2/3 - 1/6

-X= 4/6 - 1/6

-X = 3/6

-x = 1/2

x = -1/2

-1/2 need to be subtracted from -2/3

to get -1/6 as a answer