Help finding interest rates using two accounts.

Question

Helen invests $1500 in one account and $2100 in an account paying 3% higher interest rate. In one year she earned $279 in interest. At which rates did she invest?

Answer 1

1500X + 2100(.03) = 279

1500X = 279 - 63 = 216

X = 216/1500 = 0.144 = 14.4% for $1500

$2100 at 3%

279/3600 = 0.775 = 7.75% average rate of return on the total invested

3 is within 4.75 of 7.75

14.4 is within 6.65 of 7.74

6.65/4.75 = 1.4, You need 1.4 time as much invested at 3% as at 14.4%

2100/1500 = 1.4