Nathaniel can weld a railing in 75 minutes. Brenda can weld a railing 25 minutes faster. If they work together, how many minutes does it take them to weld the railing?

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Answer 1 · 2017-12-28T19:45:52

We will treat the times it takes them to weld the railing as rates and add them together.

Okay. We're going to start by defining the speeds.

Nathaniel can do 1 railing per 75 minutes.
Brenda can do 1 railing per 50 minutes (25 less than 75.)

We will add the two rates because they are working together.

#(1" railing")/(75" minutes") +(1" railing")/(50" minutes")#

We use the common denominator of #150 " minutes"#.

#(1*color(green)2" railings")/(75*color(green)2" minutes") +(1*color(green)3" railings")/(50*color(green)3" minutes")#

#(2" railings")/(150" minutes") +(3" railings")/(150" minutes")#

#(5" railings")/(150" minutes")=(1" railing")/(30" minutes")#

They weld the railing in #30" minutes"#.