<PRE><B>Question 1012240</B>
equation for elf 1 is 20 + 5x.
equation for elf 2 is 28 + 3x.


x is the number of hours.
5x is the number of additional trains elf 1 can make in x hours.
3x is the number of additional trains elf 2 can make in x hours.


you want to know how many hours are required for each to make the same number of trains.


20 + 5x is the total number of trains elf 1 can make in x hours.
28 + 3x is the total number of trains elf 2 can make in x hours.


if you want the total number of trains each makes to be the same, then set 20 + 5x equal to 28 + 3x.


your equation is 20 + 5x = 28 + 3x.


solve for x in this equaiton and you should have your answer.


start with 20 + 5x = 28 + 3x.


subtract 20 from both sides of this equation and subtract 3x from both sides of this equation to get 5x - 3x = 28 - 20


combine like terms to get 2x = 8


divide both sides of this equation by 2 to get x = 4.


they should have built a total of the same number of trains in 4 houjrs.


elf 1 will have built a total of 20 + 5*4 = 40 trains. 


elf2 will have built a total of 28 + 3*4 = 40 trains.


solution is good.


it will take 4 additional hours and they both will have made a total of 40 trains each.


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