The fractions you have to add are 1/3 and -5/6

The denominators are "3" and "6"
The common denominator between both numbers is 6.
6*1=6
3*2=6
Multiply 1/3 by factor 2 so that both fractions will have the same denominator

Now you can add both fractions

The result is not in its most reduced form, to siplify the fraction divide both the numerator and denominator by 3

The result is -1/2, in the number line: