The world brand of rivet placement is 11209 rivets in 9 hours and belongs to j. mair of ireland. if another person places 11209 rivets in 10 hours, how long will it take both of them, if they work together, to place the 11209 rivets?

4.74 hours

Step-by-step explanation:

Given that both person have to place same number of rivets that is

11209

first person take 9 hours to complete the work

hence 1 hour work of 1st person is of total work

second person takes 10 hours to complete the same work

hence 1 hour work of 2nd person is

Now if both work together then

1 hour work of both person = =

thus working together they need hours = 4.74 hours to complete the whole work which is placing 11209 rivets