The output value of a factory in January, February, and March of this year is respectively recorded as: 90,000 yuan, -150,000 yuan, and 120,000 yuan, (a positive number indicates an increase in output value compared with the same period last year, and a negative number indicates a decrease in output value compared with the same period last year). How much is the output value in the first quarter of this year compared with the output value in the first quarter of last year? (fill in how much to increase or decrease)
某厂今年一月、二月、三月的产值分别记为：9万元，-15万元，12万元，(正数表示比去年同期产值增加，负数表示比去年同期减少)．今年第一季度的产值比去年第一季度的产值多少万元．(填增加或减少多少)
<gadget id="calculator">9 + (-15) + 12</gadget>
<output>6</output>

<result>6</result>