Answer:
without marketing with marketing differential
plan plan amount
total sales 8,200 8,550 350
sales revenue $164,000 $171,000 $7,000
variable costs ($73,800) ($76,950) ($3,150)
contribution $90,200 $94,050 $3,850
margin
contribution 55% 55% -
margin ratio
fixed and ($20,000) ($23,000) ($3,000)
marketing costs
operating $70,200 $71,050 $850
income
The return on investment (ROI) from your marketing plan = $850 / $3,000 = 28.33%
If the required ROI is 12%, then you could charge = net increase in operating profits / (1 + required ROI) = $3,850 / 1.12 = $3,437.50