A project can be completed by A in 30 days, B in 45 days, and C in 90 days. Now A, B, and C are working together to complete the project. In the process of work, A rested for 2 days, B rested for 3 days, and C did not rest, and finally completed the project. How many days did the project take before and after?
一项工程，甲单独完成要30天，乙单独完成要45天，丙单独完成要90天．现由甲、乙、丙三人合作完成此工程．在工作过程中甲休息了2天，乙休息了3天，丙没有休息，最后把这项工程完成了．问这项工程前后一共用了多少天？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 2</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 45</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">(1/45) * 3</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) + (1/15) + 1</gadget>
<output>17/15 = around 1.133333</output>

<gadget id="calculator">1 / 90</gadget>
<output>1/90 = around 0.011111</output>

<gadget id="calculator">(1/30) + (1/45) + (1/90)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(17/15) / (1/15)</gadget>
<output>17</output>

<result>17</result>