Solving equations. 13x-5x=128+72; (1/4)x-35.8=4.2.
解方程．13x-5x=128+72；(1/4)x-35.8=4.2．
<gadget id="calculator">4.2 + 35.8</gadget>
<output>40</output>

<gadget id="calculator">40 * 4</gadget>
<output>160</output>

<result>160</result>