alrighty
each necklace costs him 7 dollars but he gets 10 dollars from selling them
so his profit per necklace=10-7=3 per necklace
so we want to find how many necklaces he needs to make and sell to cover the initial investment
the cost is 387
divide it by the profit per necklace
387/3=129
needs to make 129 necklaces
the total expenses would be equal to the total sales
ok, the sales are 10 dollars and 129 necklaces so total sales is 1290 dollars and so then the expenses are 1290 dollars
129 necklaces
total expensese is $1290
total sales is $1290