Question 1157349


 If a customer uses 420 minutes,
 the monthly cost will be $64. 

C =mx + y

C= total cost 
m is cost per minute
y is the fixed amount per month

64 =420m +y

If the customer uses 910 minutes, the monthly cost will be $113. 
113 =910m +y
420.00	m	+	1.00	y	=	64.00		
								
								
910.00	m	+	1.00	y	=	113.00	.............2	
Eliminate 	y							
multiply (1)by		-1.00						
Multiply (2) by		1.00						
-420.00	m		-1.00	y	=	-64.00		
910.00	m		1.00	y	=	113.00		
Add the two equations								
490.00	m				=	49.00		
/	490.00							
m	=	0.10						
plug value of			m	in (1)				
420.00	m	+	1.00	y	=	64.00		
42.00		+	1.00	y	=	64.00		
			1.00	y	=	22. costy	=	22.00		
Ans	m	=	0.10					
	y	=	22.00					


cost per minute 10 cents
Fixed monthly charge $ 22 

 the total monthly cost if 863 minutes are used.

plug m,y,x to get monthly