Answer with Explanation:
As we know that:
Selling Price = Cost + Markup
And using markup on cost, the cost is always 100%
So
Selling price %age = 100% + 20% = 120%
So
Cost 100% = $150 * 100% / 120% = $125
But when percent markup on selling price is used, then the selling price is always 100% which is equal to $125.
So
Selling price 100% = Cost 80% + Markup 20%
$125 = Cost 80% + ($150-$125)
$125 - $25 = Cost
Cost = $100
Equivalent rate of percent markup on cost will be:
Equivalent rate of percent markup on cost = $50 / $100 = 50%
The answer is 50%.