A trapezoidal tank with a depth of 2 meters, an opening of 10 decimeters wide and a bottom of 4 decimeters, what is the side area of the tank in square meters?
一个侧面是梯形的水槽，深2米，它的开口宽10分米，底是4分米，这个水槽的侧面积是多少平方米．
<gadget id="calculator">10 / 10</gadget>
<output>1</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">(7/5) * 1</gadget>
<output>7/5 = around 1.4</output>

<result>7/5 = around 1.4</result>