On Wednesday, a local hamburger shop sold a combined total of 387 hamburgers and cheeseburgers. The number of cheeseburgers sold was two times the number of hamburgers sold. How many hamburgers were sold on Wednesday?
C (cheeseburgers) =2H (hamburgers)
C+H=387
2H+2H =387
3H=387
H=129
(So, it the lesson it explains how to do the work (view above) but I don't understand how they get 129 out of 387, can someone explain that to me?)

Question

On Wednesday, a local hamburger shop sold a combined total of 387 hamburgers and cheeseburgers. The number of cheeseburgers sold was two times the number of hamburgers sold. How many hamburgers were sold on Wednesday? 
C (cheeseburgers) =2H (hamburgers) 
C+H=387 
2H+2H =387 
3H=387 
H=129 
(So, it the lesson it explains how to do the work (view above) but I don't understand how they get 129 out of 387, can someone explain that to me?)

simplysadie · Answer

Lesson

simplysadie · Answer

It's fine thanks tho

Shadow · Answer

Do you understand how they got C = 2H ?

simplysadie · Answer

Yeah, its the number of cheeseburgers sold was two times the number hamburgers sold

Shadow · Answer

and C + H = 387

You understand how they got that?

simplysadie · Answer

Yes that's the amount of both the cheeseburgers and hamburgers sold together

Shadow · Answer

Correct. They want us to solve for " How many hamburgers were sold on Wednesday? "

We have two equations.

C = 2H
C + H = 387

We want to solve for H. But we can't solve for it with another variable in they. We need some way to solve for H, and that requires us to represent C in terms of H. So we substitute 2H in for C. That's how they get:

$$3H = 387$$

Then they solve for the variable, isolating it by dividing by three

$$H = 129$$

They sold 129 hamburgers on Wednesday.

simplysadie · Answer

Okay, that makes sense now. Thanks, Shadow.

Shadow · Answer

No problem.

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