7x-7=4x-1.
7x-7=4x-1．
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">7 - 4</gadget>
<output>3</output>

<gadget id="calculator">6 / 3</gadget>
<output>2</output>

<result>2</result>