Question 406602
let brother drive for x hours
sister drive for y hours

..
x+y =10

..
d=time * speed

55x+60y=580

x+y=10	.............1	
55x+60y	=580.............2	
								
 					-55			
Multiply (2) by					1			
-55x+-55y=-550		
55x+60y	=580		
								
Add the two equations								
								
5y=30		
								
/5							
								
y=6 sister's speed
distance she drove = 6*60= 360 miles					
Plug value of y in 							
x+y=10		
x+6=10		
x=4 brother's speed
distance brother drove = 4*55=220 mile


TOTAL = 580 miles