Question 872872
A trader bought paraffin for $500. He paid $x for each litre.

Number of litres he bought = 500/x

a) Due to a leak he lost 3 litres of paraffin.

balance = (500/x) -3 

He sold the remainder for $1 per liter more than he paid for it.

{{{((500/x)-3)(x+1)}}} = total sales


Profit ={{{((500/x)-3)(x+1)-500}}} 
 
 Write an expression in terms of x for his total income.

 
B) He made a $20 profit.

{{{((500/x)-3)(x+1)-500}}}=20
 
c) How many litres of paraffin did he sell?

{{{((500/x)-3)(x+1)=520}}}

mulyiply by 
(500-3x)(x+1) =520x

500x+500-3x^2-3x=520x

3x^2+23x-500=0

solve 

a=	3	,	b=	23	,	c=	-500	
								
b^2-4ac=	529	+	6000					
b^2-4ac=	6529							
{{{	sqrt(	6529	)=	80.8	}}}			
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}								
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}								
x1=(	-23	+	80.8	)/	6			
x1=	9.63							
{{{x2=(-b-sqrt(b^2-4ac))/(2a)}}}								
x2=(	-23	-80.8	) /	6				
x2=	-17.30							
Ignore negative value								
cost per litre = 9.63
that works out to 51.92 litres

he sold 48.92 litres @ 10.63

= 520.02