Bonita Company has a materials price standard of $2.60 per kilogram. 3930 kilograms of materials were purchased at $2.30 a kilogram. The actual quantity of materials used was 3630 kilograms, although the standard quantity allowed for the output was 3530 kilograms. Bonita Company's total materials variance is

$919 F.

$1040 U.

$780 U.

$100 F.