mathematics questions..

If the L.CM. of 3, 21 and a is 147 where a does not equal to 147, find a.
Answer.49(49x3=147)

What means by If the L.C.M. if?

A, B 兩人同時同向同一目的地前進, Ａ在Ｂ的後面200 米。兩人步行的平均速率分別是8米/秒 及 6米/秒。問100秒後兩人相距幾米？
兩人相距:
6x100+200-8x100
=600+200-800
=800-800
=0(m)

2007-01-06 23:08:56 補充：
What means byIf the L.C.M. of and n is 63[of what and n?]You have to give me that number or I cannot give you the answer.

1)since the second small multiple of 147 is294
the lcm of 3,21,147 is 294

2)唔明你條題目
3)the distant between a and b=8*100 -(6*100 +200)
=0m

2007-01-06 20:11:12 補充：
e...原來睇錯左條題目1)since the l.c.m. of 3,21,a is 147a is 49 where a is not equal; to 1472)the possible values of n are 7,9,63