Hi Jessica,

One is recommended to start drawing model from where the subjects /persons have the same / equal amount of money / item.

As this appears at the end, we can apply the <Work Backwards> technique and using <Model>, we have the following ...

*** - buffer space for alignment purpose

<After>

B |----------------------|

S |----------------------|

M |----------------------|

<Process>

B: -(2/5), S: -500,

M (spending) : B (spending) = 3 : 4

In <work Backwards>, we just reverse the process.

B:

B was left with 3 parts(p) ; by adding 2p, it will be B's original money. Likewise, divide all 3 equal portions into 3p each.

S: + 500

Ratio of M : B (Spending) = 3 : 4:

Divide B's spending of 2p into 4 equal units (u); Add 3u to M (M's spending);

Likewise, the 3p of each B, S, M is divided into 6u each.

So the <Before> model is derived as shown:

*********************<--- 4u --->

**<-------- 3p -------><--- 2p --->

B |---|---|---|---|---|---|---|---|---|---|**--

S |---|---|---|---|---|---|<-500->*******|--> 5000

M |---|---|---|---|---|---|---|---|---|*****--

**<-------- 6u -------><- 3u ->

Hence, we have ...

25u --> 5000 - 500 = 4500

1u --> 4500 รท 25 = 180

(a) Each of them was left with 6u --> 6 x 180 = **$1080**

(b) Total (B + M) had at first = 10u + 9u = 19u

*** 19u --> 19 x 180 = **$3420**

=================================================

Trust the above helps.

Do let me know again should there be any clarification.

Cheers,

Edward