There is a batch of cement at the infrastructure construction site, 7 tons were used for the first time, 0.75 tons more than the second time, and 5.5 tons remained. How many tons is this batch of cement?
基建工地有一批水泥，第一次用去7吨，比第二次多用去0.75吨，还余下5.5吨．这批水泥一共有多少吨？
<gadget id="calculator">7 - 0.75</gadget>
<output>6.25</output>

<gadget id="calculator">7 + 6.25 + 5.5</gadget>
<output>18.75</output>

<result>18.75</result>