Last year Anne invested a total of $6,400. She invested part of it in a certificate of deposit that earned 2% interest for the year. The rest of the investment was put into bonds that earned 6% interest for the year. Anne earned 3.75% in interest overall. How much money did Anne put into each type of investment?

Suppose Anne invested $x in certificate of deposit and $ (6400-x) in bonds.

Interest rate earned in certificate deposit will be:

2/100*x=0.02x

Interest earned in bonds will be:

6/100 * (6400-x)

= (364-0.06x)

Total amount of interest earned was 3.75%, this is equal to:

3.75/100*6400

=240

hence we conclude that:

0.02x + (364-0.06x) = 240

0.02x+364-0.06x=240

0.02x-0.06x=240-364

-0.04x=-124

x=-124 / (-0.04)

x=$3100

hence the amount invested in certificate was $3100 and the amount invested in bonds was (6400-3100) = $3300