數學.............20分

10. 120個郵票平分給Mary, Peter同Betty. 如果Peter 分得的是Mary的一半, 而Betty 分得的是Peter 的3倍, 問每人實際分得多少?
答: 假設Peter 分得 x 個郵票
那麼 Mary 得 2x 個郵票, Betty 得 3x個郵票
加起來, x + 2x + 3x = 120 => 6x = 120 => x = 120 / 6 = 20
所以, Peter 得20個, Mary得2*20 = 40個，Betty 得3*20=60個
驗: 20 + 40 + 60 = 120

11. 兩個連續雙數的和是86, 問那兩數是什麼?
答: 假設較小的數是 x, 較大的便是 x + 2
加起來, x + (x + 2) = 86 => 2x + 2 = 86 => x = (86 - 2) / 2 = 84 / 2 = 42
所以，那2數是42和44.
驗: 42 + 44 = 86

12. y+4分之3y=28
答: y + 3y / 4 = 28
(4y + 3y) / 4 = 28
7y / 4 = 28
所以，y = 28 * 4 / 7 = 16
驗: 16 + 3/4 * 16 = 16 + 12 = 28

10. Let x be the no. of stamps of Mary
1/2x+x+3(1/2)x=120
1/2x+x+3/2x=120
3x=120
x=40
Mary=40
Peter=20
Bettey=60

11. Let x be the smaller no.
x+x+2=86
2x=84
x=42
Smaller no.=42
Bigger no.=44

12. y+4/3y=28
7/3y=28
y=12

10.
P = 1/2 M (Peter 數量只得 Mary 一半)
B = 3 P (Betty 是 Peter 的3倍)
M + P + B = 120 (120 個郵票分給三個人)

Therefore, P = 20; M = 40; B = 60

11.
X + (X+2) = 86
X = 42

12.
y + 3/4y = 28
y = 16

10.一百二十個郵票全分給瑪莉(mary),彼得(peter)和比蒂(betty)。如果彼得得到的郵票是瑪莉的一半,而比蒂所得的是彼得的三倍。那麼他們每人所得的郵票是多少呢?

答10. Let the no. of stamps that peter has be x.
and the no. of stamps that mary has be y.
and the no. of stamps that betty has be z.
2y=x ----(1)
3y=z ----(2)
x+y+z=120 ---(3)
(so,) 2y+y+3y=120
6y=120
y=20
(then,) x= 2X20=40
z= 3X20=60
Therefore, Mary has 40stamps,Peter has 20 stamps and Betty has 60 stamps.

11.兩個雙數連續數的和是86。找出這兩個數。
答11. Let the first no. be x.
Let the consecutive even no. be y.
x+y=86---(1)
y=x+2 ----(2)
(so,) x+x+2=86
2x=84
x=42
Therefore,the numbers are 42and44.

答12. y+4/3y=28
7/3y=28
y=12