Answer:
\frac{d}{8}
Step-by-step explanation:
If d is the total amount, and Helen has 8 nieces, we divide d by 8 to get the answer. The answer is 
132°
You have to put them in an equation...the equation is 5x+57=8x+12.
Cancel 5x from both sides to get 57=3x+12 then you cancel the 12 from both sides to get 45=3x and finally you divide 45 by 3 to get 15 after that you substitute the x for 15 and get 132°
If the man stays hyradted enough then he can go 8 days without sleep