There are three oil barrels, A, B, and C. A barrel contains (3/4) kilograms of oil, and B barrel contains (4/5) kilograms of oil. The oil contained in barrel C is less than the sum of the two barrels of A and B (7/10 )kilogram. How many kilograms of oil in a barrel of propylene?
甲、乙、丙三个油桶，甲桶装油(3/4)千克，乙桶装油(4/5)千克，丙桶装的油比甲、乙两桶之和少(7/10)千克．丙桶装油多少千克？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(4/5) - (7/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(3/4) + (1/10)</gadget>
<output>17/20 = around 0.85</output>

<result>17/20 = around 0.85</result>