已知a.b两地相距30千米,小华早上8点骑车从a地去b地,去时顺风,11点整到达b地：第二天早上八点,他从b地按原路返回,应为顶风,下午两点整才回到a点.他在两天往返途中,是否有这样一个时刻：两

已知a.b两地相距30千米,小华早上8点骑车从a地去b地,去时顺风,11点整到达b地：第二天早上八点,他从b地按原路返回,应为顶风,下午两点整才回到a点.他在两天往返途中,是否有这样一个时刻：两
已知a.b两地相距30千米,小华早上8点骑车从a地去b地,去时顺风,11点整到达b地：第二天早上八点,他从b地按原路返回,应为顶风,下午两点整才回到a点.他在两天往返途中,是否有这样一个时刻：两天往返途中均在此时刻到打同一地点?若有,这点距a点多少千米?

已知a.b两地相距30千米,小华早上8点骑车从a地去b地,去时顺风,11点整到达b地：第二天早上八点,他从b地按原路返回,应为顶风,下午两点整才回到a点.他在两天往返途中,是否有这样一个时刻：两
第一程时速10km/h,第二程时速5km/h,问题可以看成两个人分别以10km/h和5km/h的速度从a和b出发,然後求相遇的时间和地点.所以答案是早上10点,距a地20千米处这个问题,假如两次小华的车速是一样的情况下.这个时刻是有的啊!应该是10点的时刻啊.我们可以设车速为X,风速为Y所以可得3（X+Y）=30；6（x-y）=30.得到X+Y=10,X-Y=5；然后再设应该在小华出发后的T时科,打同一个地点经过.所以可得T（X＋Y）＋T（X－Y）＝30.得到T＝2.即是十点时刻.

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这个问题，假如两次小华的车速是一样的情况下。这个时刻是有的啊！！应该是10点的时刻啊。我们可以设车速为X,风速为Y所以可得3（X+Y）=30；6（x-y）=30.得到X+Y=10，X-Y=5；然后再设应该在小华出发后的T时科，打同一个地点经过。所以可得T（X＋Y）＋T（X－Y）＝30。得到T＝2.即是十点时刻。...

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这个问题，假如两次小华的车速是一样的情况下。这个时刻是有的啊！！应该是10点的时刻啊。我们可以设车速为X,风速为Y所以可得3（X+Y）=30；6（x-y）=30.得到X+Y=10，X-Y=5；然后再设应该在小华出发后的T时科，打同一个地点经过。所以可得T（X＋Y）＋T（X－Y）＝30。得到T＝2.即是十点时刻。

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第一程时速10km/h，第二程时速5km/h，问题可以看成两个人分别以10km/h和5km/h的速度从a和b出发，然後求相遇的时间和地点。所以答案是早上10点，距a地20千米処