Just convert the -2/3 to sixths. To do this, you multiply the denominator and numerator by 2 to make it equivalent to -2 1/6's denomenator (6). 2 times -2 is -4 and 3 times -2 is -6. This means -2/3 is equal to -4/6. As a result -2 1/6 - 4/6 is -2 5/6.
