Min had a total of 21 pieces of $50 and $10 notes at first. She spent ³₈ of the number of $50 notes and received another 5 pieces of $10 notes from her mother. After that, the number of $10 notes she had was ¹₂ of the remaining notes. How much money did Min have at first?

	$50	$10	Total
Before	8 u	5 u - 5	21
Change	- 3 u	+ 5
After	5 u
Comparing $50-notes and $10-notes	1x5 = 5 u	1x5 = 5 u

The number of $50-notes and $10-notes in the end is the same.

The number of $50-notes in the end is repeated.  Make the number of $50-notes in the end the same. LCM of 1 and 5 is 5.

Number of notes at first
= 8 u + 5 u - 5
= 13 u - 5

13 u - 5 = 21
13 u = 21 + 5
13 u = 26

1 u = 26 ÷  13 = 2

Number of $50-notes at first
= 8 u
= 8 x 2
= 16

Total value of $50-notes at first
= 16 x 50
= $800

Number of $10-notes at first
= 5 u - 5
= 5 x 2 - 5
= 10 - 5
= 5

Total value of $10-notes at first
= 5 x 10
= $50

Amount that Min had at first
= 800 + 50 
= $850

Answer(s): $850