A package of 5 pens sells for 51 yuan, and a package of 8 pens sells for 72 yuan. (The pens can only be sold in a box.) Teacher Zhang plans to buy 1 pen for each of the 49 students in the class. What is the minimum cost he will spend.
钢笔5支包装售51元，8支包装售72元，(钢笔只能整盒卖)张老师打算给全班49名学生每人买1支钢笔，他最少要花多少元．
<gadget id="calculator">51 * 5</gadget>
<output>255</output>

<gadget id="calculator">72 * 3</gadget>
<output>216</output>

<gadget id="calculator">255 + 216</gadget>
<output>471</output>

<result>471</result>