(10分)急!!!!中一英數

Let A be the number of hours John spends on studying, and B be the number of hours Simon spends on studying :
A = 3B....................(1)
This week :
A + 6 = 2(B + 6)
A + 6 = 2B + 12
A = 2B + 6.................(2)

Sub (1) into (2) :
3B = 2B + 6
3B - 2B = 6
B = 6

Thus, Simon spend 6 hours on studying...(part b answer)
Thus, John spend 18 hours on studying...(part a answer)

2007-09-04 08:04:54 補充：
ok...轉中文:其實我上面條數仲有少少出入...因為我係計左上個星期的，並不是今個星期...所以要加多少少...設A為原本John花於學習的時間，而B為原本Simon花於學習的時間...

2007-09-04 08:05:46 補充：
A = 3B....................(1)This week : A 6 = 2(B 6)A 6 = 2B 12A = 2B 6.................(2)Sub (1) into (2) :3B = 2B 63B - 2B = 6B = 6

2007-09-04 08:08:13 補充：
所以原本John花於學習的時間是6小時，故這個星期John花於學習的時間是(6 6=12)小時而原本Simon花於學習的時間，故這個星期Simon花於學習的時間是(18 6=24)小時

4.The number of hours John spends on studying is normally three times that of Simon.This week,each of them spends an additional 6 hours on studying .As a result ,the number of hours John spends on studying is twice that of Simon.How many hours in this week dose


(a)John spend on studying?
Let John spends X hours on studying, Simon spends Y hours on studying.

X=3Y -------------------- (1)

therefore, X+6 = 2(Y+6)
x+6=2Y+12 ----------------(2)

substitue (1) into (2), 3Y+6=2Y+12
Y=6
Thus, John spends 3Y=18 hours on studying.

(b)Simon spend on studying?

Refer to the above, Simon spends 6 hours on studying

Let x hours be the time John spends on studying this week
and y hours be the time Simon spends on studying this week.
x-6=3(y-6) - (1)
x=2y - (2)
sub (2) into (1) , 2y-6=3(y-6)
y=12
x=2(12) =24
therefore (a) John spends 24 hours on studying this week.
(b) Simon spends 12 hours on studying this week.