Xinhua Farm has built a 7.5-kilometer-long canal for 4 days, and 0.65 kilometers per day. How many kilometers are left?
新华农场修一条长7.5千米的水渠，已经修了4天，每天修0.65千米，剩下多少千米？
<gadget id="calculator">4 * 0.65</gadget>
<output>2.6</output>

<gadget id="calculator">7.5 - 2.6</gadget>
<output>4.9</output>

<result>4.9</result>