I need help ASAP thank you :)

A restaurant budgeted to sell 500 meals for $20 each in May. It actually sold 480 meals at an average of $19 each. a. How much is the Static-Budget Variance? Ca. $880 U Ob. $880 F Oc. $480 F Od $480 V Oe. 400 F Of. 400 U b. How much is the Flexible-Budget Variance? Ca. $880 U Ob. $880 F Oc. $480 F Od. $480 U Oe. 400 F Of. 400 U c. How much is Sales-Volume Variance? Ca. $880 U Ob. $880 F Oc. $480 F Od $480 U Oe. 400 F Of. 400 U