A+B=120, if A is reduced by 30 and B is increased by 30, what is the sum at this time?
A+B=120，如果A减少30，B增加30，那么此时的和是多少？
<gadget id="calculator">120 - 30</gadget>
<output>90</output>

<gadget id="calculator">90 + 30</gadget>
<output>120</output>

<result>120</result>