Uncle Zhang needs to transport (13/9) tons of cement by car, the first time (2/9) tons, and the second time (4/9) tons. How many tons are left to be transported?
张叔叔用汽车要运走(13/9)吨水泥，第一次运走(2/9)吨，第二次运走(4/9)吨．还剩多少吨没运走？
<gadget id="calculator">13 / 9</gadget>
<output>13/9 = around 1.444444</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(13/9) - (2/9) - (4/9)</gadget>
<output>7/9 = around 0.777778</output>

<result>7/9 = around 0.777778</result>