SOLUTION: Girl A can make one dress in 2 hours; girl B can make one dress in 4 hours; how long to make 12 dresses?

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Question 897481: Girl A can make one dress in 2 hours; girl B can make one dress in 4 hours; how long to make 12 dresses?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
a=2
b=4
1/a+1/b=1/x
1/2+1/4=1/x
1/2+1/4=3/4
1/x=3/4
x=4/3 hour to make one dress together
4/3*12=16 hours working together to make 12 dresses.