3 times of a number plus 4 times of this number, the sum is 1.68, find this number.
一个数的3倍加上这个数的4倍，和是1.68，求这个数．
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">1.68 / 7</gadget>
<output>0.24</output>

<result>0.24</result>