The construction team mixes cement, yellow sand, and stones in a ratio of 2:3:5 to make a concrete. It is known that the cement is 7.2 tons less than the stones. So, how many tons of materials are needed to make this concrete?
建筑队把水泥、黄砂、石子按2：3：5的比例配制成一种混凝土，已知水泥比石子少7.2吨，那么，配制这种混凝土一共需要用材料多少吨？
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">7.2 / 3</gadget>
<output>2.4</output>

<gadget id="calculator">2.4 * 2</gadget>
<output>4.8</output>

<gadget id="calculator">2.4 * 3</gadget>
<output>7.2</output>

<gadget id="calculator">2.4 * 5</gadget>
<output>12</output>

<gadget id="calculator">4.8 + 7.2 + 12</gadget>
<output>24</output>

<result>24</result>