Duo, Inc., carries two products and has the following year-end income statement (000s omitted):

PRODUCT AR-10 PRODUCT ZR7

BUDGET/ACTUAL BUDGET/ACTUAL

UNITS 2000, 2800 6000, 5600

SALES 6000,7560 12000,11760

VARIABLE COST 2400,2800 6000,5880

FIXED COST 1800,1900 2400,2400

TOTAL COST 4200,4700 8400,8420

OPERATING COST 1800,2860 3600,3480

If products AR-10 and ZR-7 are substitutes for each other, a sales mix and sales volume variation for the combined products can be calculated. If this combination is calculated, the net effect on profit of the change in the unit sales mix is: (Round intermediate calculations to five significant digits, and your final answer to the nearest whole dollar amount.)

NEED HELP WITH COMPUTATION AND FORMULA