SOLUTION: It takes Mr. Jhonson 84 minutes to clean the cafeteria by himself. It takes Ms. Lopez 70 minutes. How long will it take if they work together

Algebra ->  Customizable Word Problem Solvers  -> Numbers -> SOLUTION: It takes Mr. Jhonson 84 minutes to clean the cafeteria by himself. It takes Ms. Lopez 70 minutes. How long will it take if they work together      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 723737: It takes Mr. Jhonson 84 minutes to clean the cafeteria by himself. It takes Ms. Lopez 70 minutes. How long will it take if they work together
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of working
( 1 cafe cleaned ) / ( 84 min ) + ( 1 cafe cleaned ) / ( 70 min ) = ( 1 cafe cleaned ) / t
where +t+ = time in min if they work together
+1%2F84+%2B+1%2F70+=+1%2Ft+
Multiply both sides by +70%2A84t+
+70t+%2B+84t+=+70%2A84+
+154t+=+5880+
+t+=+38.1818+ min
This is about 38 min 11 sec working together