Hongfu Supermarket bought 100 dresses and spent 4280 yuan. Now the supermarket sells to customers at 78 yuan each. How much can you earn after selling these skirts?
红府超市进了100件裙子花去4280元．现在超市以每件78元向顾客出售，卖完这些裙子能赚多少元？
<gadget id="calculator">78 * 100</gadget>
<output>7_800</output>

<gadget id="calculator">7_800 - 4_280</gadget>
<output>3_520</output>

<result>3_520</result>