Question about an Algebra excercise

GRE Quant Problem Solving
1

Hello. I was recently doing the Algebra Basics Fundamental Quiz #2 and checking the answers video. However, there’s one excercise whose result doesn’t match the one I got and I can’t understand why.

This is the question:

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image867×377 26.8 KB

According to the answer video, the formula to get the answer is the following: 320=(40-x) 20.

However, when I try to get the x value, I get 24 instead of 56 (the answer to the problem). I double checked with WolframAlpha and the apparent value of x is 24.

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image924×498 26.5 KB

So I’m really confused with this excercise. Can anyone explain to me what am I doing wrong?

Thanks in advance.

2

I think this was fixed later in the video if I’m not mistaken?

3

No. I did the quiz yesterday, and the answer is still 56. I rewatched the video and they leave it at 56.

4

I meant the equation.