Data for Whiteworth Ltd$.$ are shown below:

Per Unit Percentage of Sales

Sales price $ $80100$

Less: Variable expenses $5062\mathrm{.}5$

Contribution margin $ $3037\mathrm{.}5$

Fixed expenses are $$25,000$ per month, and the company is selling $2,000$ units per month.

Required:

$1-$a$.$ The marketing manager argues that a $$4,000$ increase in the monthly advertising budget would increase monthly sales by $$8,000.$ Show the effect of this change on the net income? Complete the table given below to answer the question. $($Negative amounts should be indicated by a minus sign.$)$