
James B. answered 06/10/16
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Setup a proportion for Julie
x shrimp y shrimp
---------------- = -------------
1 hour h hours
cross multiply
xh = y
h = y/x
Julie can wrap y shrimp in y/x hours
Set up a proportion for Samantha ... she works twice as fast, so she can do 2x shrimp in an hour
2x shrimp y shrimp
------------------ = ---------------
1 hr h hours
Cross multiply
2xh = y
h = y/2x
The difference between the 2 expressions represents the difference in amount of shrimp wrapped
y y
----- - ----
x 2x
2y y
= ----- - -----
2x 2x
2y - y
= ----------
2x
y
= ----
2x