<u>Solution and Explanation:</u>
calculating the increase in the net operating income is as follows:
S.no Particulars and explanation Amount
1. Sales ( $268000 + 84000 ) 352000
2. Contribution ( 1 multiply with 40 percent) 140000
3. Fied expense ( $119200 plus $6200 ) 125400
4. Net operating income ( 2 step minus 3 step) $14600
therefore, net operating income increased by $ 14600 plus $12000
Note: the sales were not given, so i have taken or assumed. Please change the figure if there is different figure of sales in the question given.