Gwen had a total of 134 pieces of $20 and $10 notes at first. She spent ²₇ of the number of $20 notes and received another 10 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 Gwen have at first?

	$20	$10	Total
Before	7 u	5 u - 10	134
Change	- 2 u	+ 10
After	5 u
Comparing $20-notes and $10-notes	1x5 = 5 u	1x5 = 5 u

The number of $20-notes and $10-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 5 is 5.

Number of notes at first
= 7 u + 5 u - 10
= 12 u - 10

12 u - 10 = 134
12 u = 134 + 10
12 u = 144

1 u = 144 ÷  12 = 12

Number of $20-notes at first
= 7 u
= 7 x 12
= 84

Total value of $20-notes at first
= 84 x 20
= $1680

Number of $10-notes at first
= 5 u - 10
= 5 x 12 - 10
= 60 - 10
= 50

Total value of $10-notes at first
= 50 x 10
= $500

Amount that Gwen had at first
= 1680 + 500 
= $2180

Answer(s): $2180