Teacher Li needs to buy 12 packs of pencils as prizes, and the original price of each pack of pencils is 5 yuan. There are currently two stationery stores engaged in promotional activities. Stationery store A: 20% discount; Stationery store B: buy 3 get 1 free. Which stationery store does Mr. Li go to to buy? How much do you need?
李老师需要买12包铅笔做奖品，每包铅笔原价统一5元．现有两家文具店正在搞促销活动，A文具店：八折优惠；B文具店：买3送1，李老师到哪家文具店买合算？需要多少元？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">5 * (3/4) * 12</gadget>
<output>45</output>

<result>45</result>