maths questions

(a)
A's mark : B' marks : C's marks = 3 : 5 : 4

Let 3k marks, 5k marks and 4k marks are the marks that gotten by A, B and C respectively.

5k - 4k = 18
k = 18

Marks that B got
= 5k marks
= 5(18) marks
= 90 marks

=====
(b)
The total marks that A, B and C got
= (3k + 5k + 4k) marks
= 12k marks
= 12(18) marks
= 216 marks
=

可以將呢個比例睇做一份份\,
總共有12份
a有3份
b有5份
c有4份
If C got 18 mraks less than B,find
即系5-4=18
呢度1份=18

(a) the marks that B got
18x5
=90

(b) the total marks that A,B and C got.
18x12
=216

經驗算成功!

2009-01-07 18:26:19 補充：
補充其他:
a=18x3=54
c=18x4=72