Algebra: A Combined Approach (4th Edition)

$b.$ and $d.$ are correct.
To write a percent as a decimal, we drop the % and move the decimal point two places to the left. $a.$ is incorrect, because $6.5$%$=0.065$ $b.$ is correct, because $7.8$%$=0.078$ $c.$ is incorrect, because $120$%$=1.2$ $d.$ is correct, because $0.35$%$=0.0035$