Answer:
The correct answer is -  72,349.2
Step-by-step explanation:
Given:
selling price = 7234.92
Initial profit = 16%
we know:
selling price = cost price + profit
Solution:
78300 = cp + 16*cp/100
profit = 78300*16/100 = 12528
cost price = 78300 - 12528 = 65772
then the profit on 10%
= 65772*10/100
= 6577.2
the new selling price = 65772+6577.2
= 72,349.2
 
        
             
        
        
        
You can use a tangent:

We have opposite = 17 and adjacent = x.

substitute:
 cross multiply
       cross multiply
 multiply both sides by √3
     multiply both sides by √3

 divide both sides by 3
      divide both sides by 3

Use the Pythagorean theorem:

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Other method.
 triangle.
 triangle.
The sides are in the ratio 
Therefore

 
 
        
             
        
        
        
Make a change of coordinates:


The Jacobian for this transformation is

and has a determinant of

Note that we need to use the Jacobian in the other direction; that is, we've computed

but we need the Jacobian determinant for the reverse transformation (from 

 to 

. To do this, notice that

we need to take the reciprocal of the Jacobian above.
The integral then changes to

