算利润题

A furniture dealer purchased a desk for $150 and then set
the selling price equal to the purchase price plus a markup that was

40 percent of the selling price.  If the dealer sold the desk at the selling
price, what was the amount of the dealer's gross profit from the purchase and
the sale of the desk?

(A)  $40

(B)  $60

(C)  $80

(D)  $90

(E) $100

S=150+40%S

S=250

求得gross profit=250-150=100