Answer:
Step-by-step explanation:
a-number of advance  tickets
s-number of same day tickets
a*40+s*25=2400
a      +s      =75
I solve  with the substitution method
s=75-a
40a+25*(75-a)=2400
40a+1875-25a=2400
15a=2400-1875
15a=525
a=525/15
a=35
so  s=75-35
s=40
 
        
             
        
        
        
Answer:

Step-by-step explanation:
Applying the chain rule

Then it becomes

In x=0
![\frac{d[tex]f'(0)=-f'(0)\\f'(0)+f'(0)=0\\2f'(0)=0\\](https://tex.z-dn.net/?f=%5Cfrac%7Bd%5Btex%5Df%27%280%29%3D-f%27%280%29%5C%5Cf%27%280%29%2Bf%27%280%29%3D0%5C%5C2f%27%280%29%3D0%5C%5C) f}{dx} =-\frac{df}{dx}[/tex]
f}{dx} =-\frac{df}{dx}[/tex]
Then

 
        
             
        
        
        
2*4=8
8/5=1.6
1.6miles:12minutes
60/12=5
5*1.6=8
Blake's avg. speed is 8mph