The cake shop made a profit of $100/3 \, \%$on every cake sold . Calculate the selling price of a $1.5$kg strawberry cake if the profit made was $\$5.40$
My workings and thoughts -
I find cost price by --
$100/3 \, \% = \$ 5.40$
$ 100\% = \$ 100$
Selling price = $100+5.40 = \$ 105.40$
Why I can't do the steps like my working above ? And I must find $400/3\, \%$ to find the selling price ? Thanks in advance ..