investment?

Question

Phyllis invested dollars, a portion earning a simple interest rate of percent per year and the rest earning a rate of percent per year. After one year the total interest earned on these investments was dollars. How much money did she invest at each rate?

At rate percent :  
At rate percent :      

Answer 1

simepel interest

start=22,000$...time=1 yeer, get 1,210$ interest

averaej=1210/22000=0.055...5.5%=averaej % interest  (just for jenral interest)

split start & sum get 4% other part get 7%

0.04*x +0.07*y=1210

x+y=22,000   or y=22,000-x

0.04*x +0.07(22000-x)=1210

0.04x -0.07x +1540=1210

-0.03x=1210 -1540 =-330

x=330/0.03

=11,000

so y=11,000