Answer :
[tex]1 \ kg=1000 \ g \ - \ \$6 \\
400 \ g \ - \ x \\ \\
\frac{1000}{6}=\frac{400}{x} \\
1000x=400 \times 6 \\
1000x=2400 \\
x=\frac{2400}{1000} \\
x=2.4[/tex]
400 grams of flour cost $2.4.
400 grams of flour cost $2.4.