The first item costs $1 and then each additional item is $0.

Please can you help me with a formula in excel to calculate the price when ordering more than one item. The first item costs $1 and then each additional item is $0.85. The quantity ordered are as follows: Cell C7=2, C10=11, C13=317, C16=101, C19=27. The corresponding totals are to be entered in D7, D10, D13, D16 and D19. All other cells in column D should us an IFERROR function to keep the cells blank. I can calculate the formula in these cells individually but unsure how I can calculate D7:D9 and then use the drag and fill down to D29 to copy the formula.