A basketball is 78 yuan. In order to promote, the store stipulates that every purchase of 5 will give 1 free. How much will Mr. Zhang pay for 30 such basketballs?
一个篮球78元．为了促销，商店规定，每买5个赠送1个．张老师买30个这样的篮球，一共要付多少元？
<gadget id="calculator">30 - 5</gadget>
<output>25</output>

<gadget id="calculator">78 * 25</gadget>
<output>1_950</output>

<result>1_950</result>