Final answer:
To add fractions with different denominators, find a common denominator and convert the fractions. Then, add the numerators while keeping the common denominator.
Step-by-step explanation:
When adding fractions with different denominators, we need to find a common denominator before adding. To do this, we need to find the least common multiple (LCM) of the denominators. In this case, the denominators are 4 and 8. The LCM of 4 and 8 is 8.
Next, we need to convert the fractions to have a common denominator of 8:
-3/4 = -6/8
5/8
Finally, we can add the fractions: -6/8 + 5/8 = -1/8