The total industrial output value of a certain city in the first half of this year was 77 billion yuan, an increase of 10% over the same period last year. How much was the total industrial output value in the first half of last year?
某市今年上半年工业总产值770亿元，比去年同期增长10%，去年上半年工业总产值多少亿元？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">770 / (11/10)</gadget>
<output>700</output>

<result>700</result>