+4 Gold Price Per 1 Kilogram 40814.73 USD.
Your Question is 2.1kg Gold =How many dollars?
You just multiple 40814.73 * 2.1 = $85710.933
I think you need to practice of cacl assignmnets to get command on such calculations. There are a lot of websites which offer such assignments to do free of cost. You need to do practice to become good in Mathematics.