Mom brought 100 yuan, and went to Tesco to buy a backpack for 69.5 yuan, and bought a water glass for 12.8 yuan. How much money does mother have left?
妈妈带100元钱，到乐购超市买一个背包用了69.5元，又买了一只水杯用了12.8元，妈妈还剩多少元？
<gadget id="calculator">69.5 + 12.8</gadget>
<output>82.3</output>

<gadget id="calculator">100 - 82.3</gadget>
<output>17.7</output>

<result>17.7</result>