甲乙两箱粉笔的盒数之比是5:1，如果从甲箱取出12盒放入乙箱后，甲乙两箱粉笔的数量比是7:5，
那么两箱粉笔共有多少盒？要列式，原因和答案谢咯~
推荐回答（5个）
比是7:5,那么两箱粉笔共有多少盒?
设乙箱有x盒粉笔,列式为(5x-12)/(x+12)=7/5,求出x=8,那么乙有8盒,甲有40盒两箱粉笔共有48盒.
设甲有5x盒,则乙有x盒
(5x-12)5=7(x+12)
25x-60=7x+84
18x-144=0
x=8
则甲有:5×8=40盒
乙有8盒
则共有48盒
设甲为5x盒,乙有x盒
那就是
(5x-12)/(x+12)=7/5
所以x=8
所以甲原为40,乙为8。所以总共48强烈要求加分
共有48盒。
因为本来甲箱粉笔有40盒,乙箱粉笔有8盒,切合5:1,从甲箱中拿12盒放入乙箱后,甲箱变成28盒,乙箱变成20盒,切合7:5.
5-1=47-5=24-2=2
12/2=6盒7*6=42盒6*5=30盒30+42=72盒
共有72盒
不懂得是否正确,愿意引用,就引用。
设甲箱粉笔的盒数之比是5k,乙箱粉笔的盒数之比是k(本来),则由“从甲箱里取出12盒放入乙箱后,甲、乙两箱粉笔的盒数比是7:5”,得:5k-12/k+12=7/5,解得:k=8,则5k=40.
所以甲箱原40盒粉笔,乙箱原8盒粉笔.
比是7:5,那么两箱粉笔共有多少盒?
设乙箱有x盒粉笔,列式为(5x-12)/(x+12)=7/5,求出x=8,那么乙有8盒,甲有40盒两箱粉笔共有48盒.
设甲有5x盒,则乙有x盒
(5x-12)5=7(x+12)
25x-60=7x+84
18x-144=0
x=8
则甲有:5×8=40盒
乙有8盒
则共有48盒
设甲为5x盒,乙有x盒
那就是
(5x-12)/(x+12)=7/5
所以x=8
所以甲原为40,乙为8。所以总共48强烈要求加分
共有48盒。
因为本来甲箱粉笔有40盒,乙箱粉笔有8盒,切合5:1,从甲箱中拿12盒放入乙箱后,甲箱变成28盒,乙箱变成20盒,切合7:5.
5-1=47-5=24-2=2
12/2=6盒7*6=42盒6*5=30盒30+42=72盒
共有72盒
设甲箱粉笔的盒数之比是5k,乙箱粉笔的盒数之比是k(本来),则由“从甲箱里取出12盒放入乙箱后,甲、乙两箱粉笔的盒数比是7:5”,得:5k-12/k+12=7/5,解得:k=8,则5k=40.
所以甲箱原40盒粉笔,乙箱原8盒粉笔.
求总盒数，需要找到对应的比例和数量。
根据题意，从甲箱拿出粉笔之前，甲箱占总数的5/6，乙箱占总数的1/6，两箱占比相差：
5/6-1/6=2/3
而从甲箱拿出粉笔给乙箱后，甲箱占比改为7/12，乙箱占比变为5/12，两箱占比相差变为：
7/12-5/12=1/6
前后相比，后者的占比差比前者少：
2/3-1/6=1/2
对应于占比差不同的是因为从甲箱拿出了12箱，这时甲箱少了12箱，乙箱多了12箱，两者箱数的差别为：
12*2=24（箱）
也就是1/2对应于24箱，总箱数为：
24÷1/2=48（箱）
两箱总数前后不变，原来甲占总数的5÷（5+1）=5/6
后来甲占总数的7÷（7+5）=7/12
少了5/6-7/12=1/4
所以那么两箱粉笔共有12÷（1/4）=48盒
祝你开心
【前】甲：乙=5：1=10：2
【后】甲：乙=7：5
每份：12÷（10-7）=4（盒）
一共：4x(10+2)=48(盒）赞同4
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