Guanghua Primary School needs to purchase 15 desks and 12 chairs. Each desk is 75 yuan, and each chair is 45 yuan. If you buy a set, you can get a discount of 5 yuan. Ask how to buy more cost-effective? At least how much money do you need?
光华小学需要购买课桌15张和椅子12把．课桌每张75元，椅子每把45元，如果成套购买可优惠5元．问怎样购买比较划算？至少需要多少钱？
<gadget id="calculator">45 - 5</gadget>
<output>40</output>

<gadget id="calculator">75 + 40</gadget>
<output>115</output>

<gadget id="calculator">115 * 12</gadget>
<output>1_380</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<gadget id="calculator">3 * 75</gadget>
<output>225</output>

<gadget id="calculator">1_380 + 225</gadget>
<output>1_605</output>

<result>1_605</result>