A schoolbag is 15 yuan cheaper after a 10% discount. How much is the original price of the schoolbag?
一个书包打九折后便宜15元，书包原价是多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 / (1/10)</gadget>
<output>150</output>

<result>150</result>