一條英文數學題,請大家幫幫忙！

Let E be the age of Eric and S be the age of his sister
E + 5 = S
S = E + 5 -----------------------(1)
6(E - 5) = S - 5
6E - 30 = S - 5
6E - S = 25----------------------(2)
sub (1) into (2),we have
6E - (E + 5) = 25
5E - 5 = 25
5E = 30
E = 6
∴Eric is 6 years old.

埃里克比他的姐妹五年年輕。五年前, 他的年齡1/6 的他的sister.how 老現在是埃里克?

Let A be the age of Eric now & B be the age of his sister now

A + 5 = B --- (1)
(B - 5) x 1/6 = A - 5 --- (2)

Put (1) into (2)

(A + 5 - 5) x 1/6 = A - 5
A / 6 = A - 5
A = 6A - 30
5A = 30
A = 6

Put A = 6 into (1)

6 + 5 = B
B = 11

Hence, Eric is 6 years old.

6 years old

Let Eric be x years old now.
x-5=(x+5-5)(1/6)
x-5=x/6
x-x/6=5
5/6x=5
x=6
Therfore Eric is 6 years old now

我的gramma好廢，唔好笑我

LetYbe Eric's age,
Y+5 be his sister's age

Y-5+(Y+5)-5=1/6ｙ+ｙ

　　 2Y-5 = 7/6Y

2Y = 7/6Y+5

2Y-7/6Y = 5

5/6Y = 5

Y = 6

so Eric is 6 years old now.

2006-12-23 21:15:27 補充：
用一元一次方就可以計到啦(。^ v ^。)