10% of Warren's savings was $28 more than 40% of Eric's savings. After Warren spent ¹₄ of his savings and Eric spent 40% of his savings, Warren had $390 more than Eric. How much was Warren's saving at first?

	Eric	Warren
Before	5 u	20 u + 280
Change	- 2 u	- 5 u - 70
After	3 u	15 u + 210
Comparing Eric and Warren in the end		390 more

10% = ¹⁰₁₀₀ = ¹₁₀

40% = ⁴⁰₁₀₀ = ²₅

¹₁₀ Warren = ²₅ Eric + 28 

Make the numerators the same. LCM of 1 and 2 is 2.
 
1x210x2 Warren = 2x15x1 Eric + 28 
220 Warren = 25 Eric + 28 

Simplify the fractions.
¹₂₀ Warren = ¹₅ Eric + 14

Let ¹₅ Eric be 1 u.

Eric's savings at first = 5 u

¹₂₀ Warren = ¹₅ Eric + 14
Let ¹₂₀ Warren be 1 u + 14.

Warren's savings at first
= 20 x (1 u + 14) 
= 20 u + 280

Savings that Eric spent
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Savings that Warren spent 
= ¹₄ x (20 u + 280)
= 5 u + 70 

Warren had $390 more than Eric in the end. If another $390 was given to Eric, the amount that each had in the end would be the same.

15 u + 210 = 3 u + 390 
15 u - 3 u = 390 - 210
12 u = 180

1 u = 180 ÷ 12 = 15

Savings that Warren had at first
= 20 u + 280
= 20 x 15 + 280
= 300 + 280
= $580

Answer(s): $580