We'll start by figuring out how many ounces of dressing she puts into the jar. To add together two mixed numbers with different denominators, we'll first find equivalent fractions with common denominators.
The two fractions are
and 
. The least common denominator of 3 and 8 is 24. Let's find equivalent fractions that have 24 as the denominator for both.
For, 
= 
For, 
= 
Now we can add the whole numbers and equivalent fractions together.
6
+ 2
= 8
Reduce the fraction by dividing the numerator and denominator by 12 to get the total dressing amount of 8 
.
Now we need to take the amount of dressing and subtract the amount that she poured out. The process will be the same as above, but we'll subtract instead of add. First, we'll find equivalent fractions using the common denominator 4.
Dressing = 
Poured out
(This can stay the same since the denomiator is already 4.
Now we can subtract:
8
- 2
= 6
The amount of dressing left in the jar is 6 fluid ounces.
The two fractions are
For
For
Now we can add the whole numbers and equivalent fractions together.
6
+ 2
= 8
Reduce the fraction
Now we need to take the amount of dressing and subtract the amount that she poured out. The process will be the same as above, but we'll subtract instead of add. First, we'll find equivalent fractions using the common denominator 4.
Dressing
Poured out
Now we can subtract:
8
- 2
= 6
The amount of dressing left in the jar is 6