Question 578471
Let   	n	be the number of 	checks	

The cost per month for these banks will be								
Acme Bank			10	+	0.25	n						
Farmers bank			12	+	0.20	n						
Acme Bank	>	Farmers bank										
10	+	0.25	n			>	12	+	0.20	n		
add  	-10	to both sides										
10+0.25	n-10	>12+0.20n-10
0.25n-12>0.2n+	2			
add  	-0.2	n										
0.05	n	>	2									
/	0.05											
n	<	40										
n	should be less than 40	for Acme Bank	to be a better deal					
												
										CHECK		
									
Plan A = Plan B		at	40	checks								
Plan A( Acme)	10	+	0.25	*	40		=		20	
Plan B ( farmers)12	+	0.20	*	40		=		20	
												
Plan A >Plan B		for 	45	checks								
Acme Bank			10	+	0.25	*	45		=		21.25	
Farmers bank			12	+	0.20	*	45		=		21