10% of Perry's savings was $9 more than 30% of Peter's savings. After Perry spent ¹₅ of his savings and Peter spent 40% of his savings, Perry had $216 more than Peter. How much was Perry's saving at first?

	Peter	Perry
Before	10 u	30 u + 90
Change	- 4 u	- 6 u - 18
After	6 u	24 u + 72
Comparing Peter and Perry in the end		216 more

10% = ¹⁰₁₀₀ = ¹₁₀

30% = ³⁰₁₀₀ = ³₁₀

¹₁₀ Perry = ³₁₀ Peter + 9 

Make the numerators the same. LCM of 1 and 3 is 3.
 
1x310x3 Perry = 3x110x1 Peter + 9 
330 Perry = 310 Peter + 9 

Simplify the fractions.
¹₃₀ Perry = ¹₁₀ Peter + 3

Let ¹₁₀ Peter be 1 u.

Peter's savings at first = 10 u

¹₃₀ Perry = ¹₁₀ Peter + 3
Let ¹₃₀ Perry be 1 u + 3.

Perry's savings at first
= 30 x (1 u + 3) 
= 30 u + 90

Savings that Peter spent
= 40% x 10 u
= ⁴⁰₁₀₀ x 10 u
= 4 u

Savings that Perry spent 
= ¹₅ x (30 u + 90)
= 6 u + 18 

Perry had $216 more than Peter in the end. If another $216 was given to Peter, the amount that each had in the end would be the same.

24 u + 72 = 6 u + 216 
24 u - 6 u = 216 - 72
18 u = 144

1 u = 144 ÷ 18 = 8

Savings that Perry had at first
= 30 u + 90
= 30 x 8 + 90
= 240 + 90
= $330

Answer(s): $330