Add 0.9 to 4 times a certain number, and the sum is 6.7. Find this number.
某数的4倍加上0.9，和是6.7，求这个数．
<gadget id="calculator">6.7 - 0.9</gadget>
<output>5.8</output>

<gadget id="calculator">5.8 / 4</gadget>
<output>1.45</output>

<result>1.45</result>