Buying the same kind of cloth, Mrs. Zhang buys 12 meters, and Aunt Li buys 7 meters. Mrs. Zhang spends 40 yuan more than Aunt Li. How much is this kind of cloth per meter?
买同一种布，张妈买12米，李婶买7米，张妈比李婶多用40元，这种布每米多少元．
<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<result>8</result>