The original price of a shampoo is 56.5 yuan, and the price is reduced to 45.9 yuan per bottle. Mom bought 4 bottles of this shampoo, how much is it cheaper?
一种洗发露原价56.5元，降价后每瓶45.9元．妈妈买了4瓶这样的洗发露，一共便宜了多少钱？
<gadget id="calculator">56.5 - 45.9</gadget>
<output>10.6</output>

<gadget id="calculator">10.6 * 4</gadget>
<output>42.4</output>

<result>42.4</result>