Question

Please help me idk this

Answer 1

Just subtract the amount he took.
Answer:
$4 \frac{1}{4}$

Answer 2

First, lets find a common denominator to our fractions so we can add them together:
$\frac{1}{2} x \frac{2}{2} = \frac{2}{4}$ 
 
Now that the denominators are the same, we can add them:
$\frac{2}{4} + \frac{1}{4} + \frac{3}{4}$

Now lets add our whole numbers:
2+1=3
And now add our fraction:
3+$\frac{3}{4} = 3 \frac{3}{4}$

Then you subract the total used from the starting amount:
8-3$\frac{3}{4} = 4 \frac{1}{4}$ fl oz