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