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Question 534358:  How do I use two variables and two equations to solve this problem. A machine in a 
pottery factory takes 3 minutes to form a bowl and 2 minutes to form a plate.  The material for a bowl costs $0.25, and the material for a plate costs $0.20.  If the machine runs for 8 hours and exactly $44 is spent for material, how many bowls and plates can be produced? How do I set it up?   
 Answer by mananth(16946)      (Show Source): 
You can  put this solution on YOUR website! let  number of bowls be x 
and plates be y
 
time taken  
3x+2y= 480  
 
Money spent 
0.25x+0.2y = 44 
multiply by 100 to eliminate the decimals 
25x+20y=4400
 
bowls	x	numbers	,	Price =		$3.00		 
plates	y	numbers	,	Price =		$9.00		 
				Total		345		 
3	x	+	2	y	=	480	.............1	 
25	x	+	20	y	=	4400	.............2	 
Eliminate y								 
multiply (1)by 		-10						 
Multiply (2) by		1						 
-30	x		-20	y	=	-4800		 
25	x		20	y	=	4400		 
Add the two equations								 
-5	x				=	-400		 
/	-5							 
x	=	80						 
plug value of 			x	in (1)				 
3	x	+	2	y	=	480		 
240		+	2	y	=	480		 
			2	y	=	480		-240 
			2	y	=	240		 
				y	=	120		 
bowls	80	numbers						 
plates	120	numbers						 
m.ananth@hotmail.ca								 
 
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