The sum of the two numbers a and b is 11.5, if a (1/10) is given to b, then b is 2.9 less than a, so how much is b less than a.
a、b两数的和是11.5，如果把a的(1/10)给b，那么b比a少2.9，原来b比a少多少．
<gadget id="calculator">11.5 - 8</gadget>
<output>3.5</output>

<gadget id="calculator">8 - 3.5</gadget>
<output>4.5</output>

<result>4.5</result>