 
    overview
  The expression  can possibly be simplified in two ways (considering a rule for the sequence of operation is not established yet.)
  
 •   (added first) and
  
 •   (subtracted first)
  
which one is correct? To resolve this, the sequence of arithmetic operations of same precedence value is established as a rule.
  
 
many answers, again
Consider . 
                One person carries out the later subtraction first   .
                Another person carries out the initial subtraction first   
                Which answer is correct? 
                To resolve this, a rule of sequence is accepted by all and agreed on. As per the rule, 
  It is wrong to do   .
  The correct order of simplification is   
  The two subtractions are in the same precedence level. This is to be handled from left to right sequence.
Consider 
  It is wrong to simplify as   
  The correct order of simplification is   . 
 The two divisions are in same precedence level. This is to be handled from left to right sequence. .
  
      
Sequence in Arithmetic Operations of Same Precedence: To simplify multiple arithmetic operations of same precedence, the operations are carried out in left to right sequence.
Consider . 
  It is wrong to do   .
  The correct order of simplification is   
  The subtraction and addition are in the same precedence level. This is to be handled from left to right sequence.
Consider 
  It is wrong to simplify as   
  The correct order of simplification is   . 
 The division and multiplication are in same precedence level. This is to be handled from left to right sequence.
      
examples
Simplify 
The answer is "". 
The division and multiplication are higher in precedence over addition. so  is to be simplified first.
 In that, the division and multiplication are of same precedence, so it is simplified from left to right. 
  
  
  
  
Simplify .
The answer is "". The multiplication is higher in precedence over subtraction and so  is to be simplified first. Then the two subtraction are in the same precedence level and so they are simplified in the left to right sequence.
  
  
  
  
      
summary
 Sequence in Arithmetic Operations of Same Precedence: To simplify multiple arithmetic operations of same precedence, the operations are carried out in left to right sequence.
      
 
Outline
The outline of material to learn whole numbers is as follows
Note:   click here for  detailed outline of Whole numbers  
•    Introduction 
     
    →   Numbers
     
    →   Large Numbers
     
    →   Expanded form
     
    →   Face and place values
     
    →   Approximation and Estimation
•    Comparison 
     
    →   Comparing two numbers
     
    →   Number line
     
    →   Predecessor & Successor
     
    →   Largest & Smallest
     
    →   Ascending & Descending
•    Addition Subtraction 
    
    →   Addtion: First Principles
    
    →   Addition: Simplified Procedure
    
    →   Subtraction: First Principles
    
    →   Subtraction: Simplified Procedure
•    Multiplication Division 
    
    →   Multiplication: First Principles
    
    →   Multiplication: Simplified Procedure
    
    →   Division: First Principles
    
    →   Division: Simplified Procedure
•    Numerical Expression 
    
    →   Introducing Numerical Expressions
    
    →   Precedence
    
    →   Sequence
    
    →   Brackets