SOLUTION: Hello could you please help me work out this word sum:2 engineers build robots for a company. Engineer A builds 10 robots in 6 hours while Engineer B builds 10 robots in 4 hours ho

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Question 845176: Hello could you please help me work out this word sum:2 engineers build robots for a company. Engineer A builds 10 robots in 6 hours while Engineer B builds 10 robots in 4 hours how long will it take them to build 10 robots it they work together
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of working to get
their rate working together
A's rate:
( 10 robots ) / ( 6 hrs )
B's rate:
( 10 robots ) / ( 4 hrs )
--------------------
Let +t+ = the time in hours for them
to build 10 robots working together
+10+%2F+6+%2B+10+%2F+4+=+10+%2F+t+
Divide both sides by +10+
+1%2F6+%2B+1%2F4+=+1%2Ft+
Multiply both sides by +12t+
+2t+%2B+3t+=+12+
+5t+=+12+
+t+=+2.4+
Convert +.4+ hrs to minutes
+.4%2A60+=+24+
Working together, they take 2 hrs 24 minutes
to build 10 robots