In the equation 2a*(2/3)=b, when b=30, a=how much.
在等式2a*(2/3)=b中，当b=30时，a=多少．
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">30 / (4/3)</gadget>
<output>45/2 = around 22.5</output>

<result>45/2 = around 22.5</result>