Question 506547
at the same time Roberto meets Juan in 11 hours. If they walk towards each other they meet in 1 hour. What are their average speeds?


Roberto speed = x mph
Juan speed = y mph
let x>y
d= 7.7 
if they go away then the catch up distance = 7.7 
the catch up speed = x-y

t= d/r
t=11
11= 7.7/(x-y)  
11x-11y=7.7
/11
x-y = 0.7..............1
.....
if they move towards 
then speed = x+y
t=1
d= 7.7
t=d/r
1=7.7/(x+y)
x+y = 7.7 ------------2
add (1) & (2)
2x=0.7 + 7.7
2x=8.4
/2
x=4.2 
Roberto speed = 4.2 mph
from (2) x+y =7.7
4.2+y=7.7
y=7.7-4.2
y=3.5 
Juan speed = 3.5 mph

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