F1數學題，急！！！求高手解

Let x be the number of students.

If there were 10 students more, each of them would have to pay $ 30
coach rent = (x+10)(30)

If there were 8 students less, each of them would have to pay $50.
coach rent = (x+-8)(50)

(x+10)(30) = (x-8)(50)

30 + 300 = 50 - 400

700 = 20x

x = 35

2014-01-01 21:25:41 補充：
If there were 8 students less, each of them would have to pay $50.
coach rent = (x-8)(50)

感覺很厲害~~，wow~~~

2014-01-07 11:36:34 補充：
真的希望<我也這麼&lt;聰明

Let x be the number of students going for the picnic.
Set a simultaneous equation for the above situation.
There is a fixed cost for the picnic. Let it be $y
y=30(x+10)
y=30x+300..........(1)
y=50(x-8)
y=50x-400...........(2)
(2)-(1)
30x-y=-300
-)50x-y=400
-20x =-700
x=35
Sub. x=35 into (1)
y=30(35)+300
=1050+300
=1350
therefore, The number of students going for the picnic is 35 and the cost paid to the coach is $1350