The sloppy calculation of 4(a+2.5) was wrongly written as 4a+2.5, so the result is much less than the original formula
小马虎计算4(a+2.5)，错写成了4a+2.5，这样所得的结果比原式少了多少
<gadget id="calculator">3 * 2.5</gadget>
<output>7.5</output>

<result>7.5</result>