The number A is 150, the number B is 15% more than A, and the number C is 20% less than B, what is the number C?
甲数是150，乙数比甲数多15%，丙数比乙数少20%，丙数是多少．
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

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

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">150 * (23/20) * (4/5)</gadget>
<output>138</output>

<result>138</result>