Yen had a total of 7 pieces of $20 and $5 notes at first. She spent ²₅ of the number of $20 notes and received another 9 pieces of $5 notes from her mother. After that, the number of $5 notes she had was ¹₂ of the remaining notes. How much money did Yen have at first?

	$20	$5	Total
Before	5 u	3 u - 9	7
Change	- 2 u	+ 9
After	3 u
Comparing $20-notes and $5-notes	1x3 = 3 u	1x3 = 3 u

The number of $20-notes and $5-notes in the end is the same.

The number of $20-notes in the end is repeated.  Make the number of $20-notes in the end the same. LCM of 1 and 3 is 3.

Number of notes at first
= 5 u + 3 u - 9
= 8 u - 9

8 u - 9 = 7
8 u = 7 + 9
8 u = 16

1 u = 16 ÷  8 = 2

Number of $20-notes at first
= 5 u
= 5 x 2
= 10

Total value of $20-notes at first
= 10 x 20
= $200

Number of $5-notes at first
= 3 u - 9
= 3 x 2 - 9
= 6 - 9
= -3

Total value of $5-notes at first
= -3 x 5
= $-15

Amount that Yen had at first
= 200 + -15 
= $185

Answer(s): $185