Jia Jia copied English words, the ratio of the completed number to the remaining number is 1:2. If 15 words are copied, the completed number is as many as the remaining ones. How many English words does Jiajia want to copy?
佳佳抄英语单词，已完成的个数与剩下的个数的比是1：2．如果抄写15个，那么完成个数与剩下的个数同样多，佳佳要抄的英语单词共有多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">15 / (1/6)</gadget>
<output>90</output>

<result>90</result>