A person climbs a mountain at a speed of 7 kilometers per hour in the morning, and in the afternoon at a speed of 5 kilometers per hour for 3 hours. He climbed a total of 43 kilometers in the morning and afternoon. How many hours did this person climb in the morning? ?
一个人爬山，早晨以每小时7千米的速度爬行，下午爬山以每小时5千米的速度爬行了3小时，整个上午和下午一共爬了43千米，请问这个人早晨爬了多少个小时？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">43 - 15</gadget>
<output>28</output>

<gadget id="calculator">28 / 7</gadget>
<output>4</output>

<result>4</result>