Willow trees planted in Lingzhao Primary School accounted for 30% of the total tree planting, and pine trees accounted for 20% of the total. There were 12 more willow trees than pine trees. How many trees were planted in Lingzhao Primary School? (Solved by two methods of equation and arithmetic)
陵照小学种植柳树占植树总数的30%，种植松树占总数的20%，柳树比松树多12棵，陵照小学共植树多少棵？(用方程和算术两种方法解答)
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/10) - (1/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">12 / (1/10)</gadget>
<output>120</output>

<result>120</result>