Thanks Yu Rong for your help!

As this is a P3 question, the kids haven’t learnt this method of applying substitution yet.

Is there an easier way to derive the answer to explain to a P3?

Separately, why is there a need to multiply equation line 2 by 2?

Hope to hear from you.
Thanks.

Hi Reb,

Substitution would be the preferred approach to this specific question. However, if the kid is still unclear, perhaps you can utilise shapes (coupled with careful explanation) to make it easier to comprehend.

Also, you are right - there is no need to multiply the equation by 2. We can also go with the usual way of finding the value of 1 LT (which is = $1.40 - 2GT), before substituting it into equation 1.

However, my initial motivations for multiplying it by 2 were to make it clearer of the kid (As there's 2 LT for both equations 1 and 3). My apologies if I'd caused any confusion.

Once again, thank you and hope this helps!

Hi Ru Yong,
Will try to see how to explain as simply as possible.

Appreciate your time in replying & the detailed explanation. Thanks very much!