The product of 4 times a certain number plus 0.9 times 3 is 6.7. Find this number.
某数的4倍加上0.9乘3的积，和是6.7，求这个数．
<gadget id="calculator">0.9 * 3</gadget>
<output>2.7</output>

<gadget id="calculator">6.7 - 2.7</gadget>
<output>4</output>

<gadget id="calculator">4 / 4</gadget>
<output>1</output>

<result>1</result>