Zeph and Justin went shopping with a total amount of $273. They had $231 left after shopping. Zeph's remaining money was 4 times the amount he paid for. Justin's remaining money was 7 times the amount he had spent.

1. How much did Justin spend?
2. How much did Justin bring along for shopping?

	Zeph	Justin	Total
Before	5 u	8 p	273
Change	- 1 u	- 1 p	- 42
After	4 u	7 p	231

(a)
Amount that Zeph and Justin spent
= 273 - 231
= $42

Amount that Zeph and Justin spent
= 1 u + 1 p

1 u + 1 p = 42
1 u = 42 - 1 p --- (1)

Amount that Zeph and Justin had left
= 4 u + 7 p 

4 u + 7 p = 231
4 u = 231 - 7 p --- (2)

Make u the same.

(1) _{x 4}
4 u = 168 - 4 p --- (3)

(3) = (2)
168 - 4 p = 231 - 7 p 
7 p - 4 p = 231 - 168

3 p = 63

1 p = 63 ÷ 3 = 21

Amount that Justin spent = $21

(b)
Amount that Justin brought along
= 8 p
= 8 x 21
= $168

Answer(s): (a) $21; (b) $168