PLEASE HELP WILL GIVE BRAINLIEST Ralph can lay down a floor tile in 5 seconds. Bob can lay down a floor tile in 4 seconds. If both boys work together, how many seconds would it take them to install 450 floor tiles?

1000 seconds

Step-by-step explanation:

You can start by finding the unit rate for each of them to lay down a tile. That is, how many tiles they can lay down in one second. Ralph can lay one down in 1/5 of a second, while Bob takes 1/4. 1/5+1/4=4/20+5/20=9/20 of a tile per second. Dividing 450 by 9/20, you get 1000 seconds. Hope this helps!

first one

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1) is right

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