10% of Oscar's savings was $36 more than 30% of Pierre's savings. After Oscar spent ²₃ of his savings and Pierre spent 40% of his savings, Pierre had $180 less than Oscar. How much was Pierre's saving at first?

	Pierre	Oscar
Before	10 u	30 u + 360
Change	- 4 u	- 20 u - 240
After	6 u	10 u + 120
Comparing Pierre and Oscar in the end		180 more

10% = ¹⁰₁₀₀ = ¹₁₀

30% = ³⁰₁₀₀ = ³₁₀

¹₁₀ Oscar = ³₁₀ Pierre + 36 

Make the numerators the same. LCM of 1 and 3 is 3.
 
1x310x3 Oscar = 3x110x1 Pierre + 36 
330 Oscar = 310 Pierre + 36 

Simplify the fractions.
¹₃₀ Oscar = ¹₁₀ Pierre + 12

Let ¹₁₀ Pierre be 1 u.

Pierre's savings at first = 10 u

¹₃₀ Oscar = ¹₁₀ Pierre + 12
Let ¹₃₀ Oscar be 1 u + 12.

Oscar's savings at first
= 30 x (1 u + 12) 
= 30 u + 360

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

Savings that Oscar spent 
= ²₃ x (30 u + 360)
= 20 u + 240 

Pierre had $180 less than Oscar in the end. If another $180 was given to Pierre, the amount that each had in the end would be the same.

10 u + 120 = 6 u + 180 
10 u - 6 u = 180 - 120
4 u = 60

1 u = 60 ÷ 4 = 15

Savings that Pierre had at first
= 10 u 
= 10 x 15
= $150

Answer(s): $150