中二數學問題

let ling original get $y
then CK get $4y/7
after ling give to CK, she became $y-600 and CK became $4y/7+600
then 6(y-600) = 5 (4y/7 + 600)
6y - 3600 = 20y/7 + 3000
6y - 20y/7 = 3000+3600
22y/7 = 6600
y = 2100
so CK got 1200
total = 3300

7x=2100 4x1200 5x1500 6x1800
所以:::::::7x+4x=5x+6x=3300

A)∵玲玲分得款項﹕志強分得款項=7﹕4
∴設玲玲分得款項7x,志強分得款項4x.
∴7x–600﹕4x+600=5﹕6
∴5(4x+600)=6(7x–600)
20x+3000=2x–3600
–22x=–6600
x=300
∴玲玲分得款項=7x=7×300=$2100
志強分得款項=4x=4×300=$1200
B)該筆款項的總數=玲玲分得款項+志強分得款項
=$2100+1200
=$3300

a)設玲玲有x元, 志強有y元
x:y = 7:4
x/y=7/4
x=7y/4...(1)

若玲玲給志強$600 , 則兩人款項之比便變成5:6..
所以 (x-600):(y+600)= 5:6
(x-600)/(y+600)= 5/6
6(x-600)= 5(y+600)
6x-3600= 5y+3000
6x=5y+6600
6(7y/4)= 5y+6600 ....because of (1)
42y = 20y + 26400
22y= 26400
y= 1200.....(2)

x= 7y/4... because of (1)
x= 7(1200)/4
x=2100

所以玲玲有$2100, 志強有$1200

b) 總數= 玲玲的錢+志強的錢
= 2100+ 1200
=3300
所以總數有$3300

7X=2100
4X=1200
5X=1500
6X=1800

總數=7X+4X=5X+6X=3300

比例差值：

7：4，5：6

=7a：4a、5a：6a

7a-5a = 2a、6a-4a = 2a

所以，2a = 600

a = 300

7(300)+4(300) = 3300

款項總數：$3300

分前：

玲玲：7(300) = 2100

志強：4(300) = 1200

分後：

玲玲：5(300) = 1500

志強：6(300) = 1800