She would have a total of 40 stamps. 
        
             
        
        
        
The negative solution is x = –1.
Solution:
Let the number be x.
Square of a number = x²
3 times a number = 3x
Difference of square of a number and 4 = 3 times that number

Subtract 3x from both sides of the equation, we get

–3x can be written as x – 4x.
 

1st bracket have common term x and bracket have –4 common term.

Take common term x + 1 outside.

<em>By zero factor principle, if AB = 0 then A = 0 or B = 0.</em>
x + 1 = 0,   x – 4 = 0
x = –1,   x = 4
The negative solution is x = –1.
 
        
             
        
        
        
Answer:Hence, x = 5, y = 0 is the required solution.
Step-by-step explanation:
 
        
                    
             
        
        
        
Well what is 30x3 (because that is how you would find what is one third of unknown) then you find the answer witch is 90$