Sorry I don’t know it right now but I can help you with some thing else
        
             
        
        
        
To solve this problem you must apply the proccedure shown below:
 1. You must make a system of equations, as below:
 2. Let's call:
 x: the number of first class tickets bought.
 y: the number of coach tickets bought.
 3. Then, you have:
 x+y=7 (First equation)
 970x+370y=3790 (Second equation)
 x=7-y
 4. By substitution, you have:
 970x+370y=3790
 970(7-y)+370=3790
 y=5
 x=7-y
 x=7-5
 x=2
 Therefore, the answer is:
 - Number of first class tickets bought=2
 - Number of coach tickets bought=5
 
        
             
        
        
        
Estimate : 23 × 67
20 (lower down, lower than 5...the last digit) × 70 (Higher, higher than 5)
=20×70
=1400 
The estimated value will be 1400
        
             
        
        
        

Differentiate both sides, treating 
 as a function of 
. Let's take it one term at a time.
Power, product and chain rules:



Product and chain rules:




Product and chain rules:




The derivative of 0 is, of course, 0. So we have, upon differentiating everything,

Isolate the derivative, and solve for it:


(See comment below; all the 6s should be 2s)
We can simplify this a bit by multiplying the numerator and denominator by 
 to get rid of that fraction in the denominator.

 
        
             
        
        
        
Answer: 
X= 35
Z=90
Step-by-step explanation:
sorry I don’t know how else to help