Mom cuts a 3.5-meter-long rope into three sections. The total length of the first two sections is 1.8 meters, and the total length of the last two sections is 2.85 meters. How many meters is the length of the middle section of the three cut ropes?
妈妈将一根3.5米长的绳子剪成3段，前两段的总长是1.8米，后两段的总长是2.85米，剪成的三段绳子中间一段长多少米．
<gadget id="calculator">2.85 - 3.5</gadget>
<output>-0.65</output>

<gadget id="calculator">1.8 + (-0.65)</gadget>
<output>1.15</output>

<result>1.15</result>