Small durians	Medium durians	Large durians
$3	$7	$9

Eric had some durians in 3 sizes. The number of medium durians was four times the number of large durians. The number of large durians were five times the number of small durians. He sold all the small and medium durians. He received $36 from selling ¹₅ of the large durians.Eric had some durians in 3 sizes. 
He sold all the small and medium durians. He received $36 from selling ¹₅ of the large durians.

1. How many medium durians did he have at first?
2. How much more did he collect from selling the medium durians than the small durians?

Small durians	Medium durians	Large durians
	4x5	1x5
1x1		5x1
1 u	20 u	5 u

(a)
The number of large durians is the repeated identity. Make the number of large durians the same.  LCM of 1 and 5 is 5.

	Small durians	Medium durians	Large durians
Before	1 u	20 u	5 u
Change	- 1 u	- 20 u	- 1 u
After	0	0	4 u

Number of large durians that Eric sold
= ¹₅ x 5 u
= 1 u

	Small durians	Medium durians	Large durians
Number	1 u	20 u	1 u
Value	$3	$7	$9
Total value	3 u	140 u	9 u

Amount that Eric received from selling of ¹₅ of the large durians = 9 u
9 u = 36

1 u = 36 ÷ 9 = 4

Number of medium durians at first
= 20 u
= 20 x 4
= 80

(b)
Amount that Eric collected more from selling the medium durians than the small durians
= 140 u - 3 u
= 137 u
= 137 x 4
= $548

Answer(s): (a) 80; (b) $548