Build a cement road with a width of 3.5 meters and a thickness of 30 centimeters. How many meters of road can be paved if 21 cubic meters of concrete are mixed? (solution by equation)
修一条宽3.5米、厚30厘米的水泥路．如果搅拌了21立方米的混凝土，可以铺多少米的路？(用方程解)
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3.5 * (3/10)</gadget>
<output>1.05</output>

<gadget id="calculator">21 / 1.05</gadget>
<output>20</output>

<result>20</result>