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# Xenon Maths Help Thread! Watch

1. Hi how do I do part b, thanks.
2. (Original post by _Xenon_)
Hi how do I do part b, thanks.
If his height at age 20 is then his height at age 12 is
3. (Original post by Zacken)
If his height at age 12 is then his height at age 12 is
What's x?
4. (Original post by _Xenon_)
What's x?
His height at age 20.
5. (Original post by Zacken)
His height at age 20.
Is it a hard question? We can't times by x when we don't know what it is!
6. (Original post by _Xenon_)
Is it a hard question? We can't times by x when we don't know what it is!
It's quite a standard reverse percentages question.

Have you studied that topic? How do you usually do a question like this?
7. (Original post by notnek)
It's quite a standard reverse percentages question.

Have you studied that topic? How do you usually do a question like this?
Not learnt reverse percentages but thanks!!
8. (Original post by _Xenon_)
Not learnt reverse percentages but thanks!!
Then you should probably learn the topic before trying questions.

Zacken has given you a way to do it using algebra. If you want to do it a different way then one of us can give you another method.
9. (Original post by _Xenon_)
Is it a hard question? We can't times by x when we don't know what it is!
I'm asking you to setup an equation involving x and then solve for x.
10. (Original post by notnek)
Then you should probably learn the topic before trying questions.

Zacken has given you a way to do it using algebra. If you want to do it a different way then one of us can give you another method.
(Original post by Zacken)
I'm asking you to setup an equation involving x and then solve for x.
153/85 * 100 ? Will that be correct?

And yeah it is in a past paper I'm reviewing to fill in the gaps.
11. (Original post by _Xenon_)
153/85 * 100 ? Will that be correct?
Yes.
12. (Original post by Zacken)
Yes.
OK thanks!!!
13. (Original post by Zacken)
Yes.
Algebra is better imo, will try that!!
14. (Original post by _Xenon_)
Algebra is better imo, will try that!!
That is the algebraic method?
15. (Original post by Zacken)
That is the algebraic method?
Nope.
16. (Original post by _Xenon_)
Nope.
Okay.
17. (Original post by Zacken)
That is the algebraic method?
Like this

153 = 85/100 * x
15300 = 85x
15300/85 = x
120 = x
18. (Original post by _Xenon_)
Like this

153 = 85/100 * x
15300 = 85x
15300/85 = x
120 = x
15300/85 is not 120.
19. (Original post by Zacken)
15300/85 is not 120.
20. (Original post by _Xenon_)
Just an arithmetical one.

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