Final result :  -3
Step by step solution :Step  1  :            3 - a Simplify   —————             21  Equation at the end of step  1  :  (a - 3)   (3 - a)  ——————— ÷ ———————     7        21   Step  2  :            a - 3 Simplify   —————              7  Equation at the end of step  2  :  (a - 3)   (3 - a)  ——————— ÷ ———————     7        21   Step  3  :         a-3      3-a Divide  ———  by  ———          7       21 
 3.1    Dividing fractions 
To divide fractions, write the divison as multiplication by the reciprocal of the divisor :
a - 3     3 - a       a - 3        21  —————  ÷  —————   =   —————  •  ———————  7        21           7       (3 - a)
 3.2    Rewrite   (3-a)    as  (-1) •  (a-3) Canceling Out : 3.3    Cancel out  (a-3)  which now appears on both sides of the fraction line.
Final result :  -3
        
                    
             
        
        
        
Answer:

Step-by-step explanation:
<u><em>The correct question is</em></u>
What value of b will cause the system to have an infinite number of solutions? 
y = 6x – b 
–3x + 1/2y = –3
we have
 ----->equation A
 ----->equation A
 -----> equation B
 -----> equation B
we know that
If the system has infinite number of solutions then, the equation A must be equal to the equation B
so
isolate variable y in the equation B

Multiply by  both sides
 both sides

 -------> new equation B
 -------> new equation B 
To find out the value of b, equate equation A and equation B


 
        
             
        
        
        
Answer:
Step-by-step explanation:
so add what you have if you one number spilt it and divide