Cost is 6 USD
Selling price is 6 + markup
Markup = 6 * 120 /100 put this expression and check again selling price
Selling price = 6 + (6 * 120) / 100
= 13,2 usd
28/11.2 = 2.5
since they are similar and openly stated as parrallelograms, you know that they have a scale of the longest edge of EFGH to the longest edge of JKLM
4.2 is the answer. Hope this answered your question