Gabby had a total of 85 pieces of $20 and $100 notes at first. She spent ³₇ of the number of $20 notes and received another 3 pieces of $100 notes from her mother. After that, the number of $100 notes she had was ¹₂ of the remaining notes. How much money did Gabby have at first?

	$20	$100	Total
Before	7 u	4 u - 3	85
Change	- 3 u	+ 3
After	4 u
Comparing $20-notes and $100-notes	1x4 = 4 u	1x4 = 4 u

The number of $20-notes and $100-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 4 is 4.

Number of notes at first
= 7 u + 4 u - 3
= 11 u - 3

11 u - 3 = 85
11 u = 85 + 3
11 u = 88

1 u = 88 ÷  11 = 8

Number of $20-notes at first
= 7 u
= 7 x 8
= 56

Total value of $20-notes at first
= 56 x 20
= $1120

Number of $100-notes at first
= 4 u - 3
= 4 x 8 - 3
= 32 - 3
= 29

Total value of $100-notes at first
= 29 x 100
= $2900

Amount that Gabby had at first
= 1120 + 2900 
= $4020

Answer(s): $4020