f.1數學一題...

There are 3 types of concert tickets:$400,$200 and $100.the number of $200 tickets sold is 4 times that of $400 tickets.the number of $100 tickets sold is 380 more than that of $200 tickets.if the total income from the tickets is $86000,find the number of $400 tickets sold.
Let x be the number of $400 tickets sold
400x + 200(4x) + 100(4x + 380) = 86000
400x + 800x + 400x + 38000 = 86000
1600x = 48000
16x = 480
x = 30 //
The number of $400 tickets sold is 30

Let x be the number of $400 tickets sold.

400x+200(4x)+100(4x+380)=86000

400x+800x+400x+38000=86000

1600x+38000=86000

1600x=48000

x=30

Therefore the number of $400 tickets sold is 30.

Let x be the number of $400 tickets sold , the price 400x
Thus the number of $200 tickets is 4x , the price 200(4x)
the number of $100 tickets is (4x+380) , the price 100(4x+380)
so , 400x+200(4x)+100(4x+380)=86000
400x+800x+400x+38000=86000
1600x=48000
x=30
Thus the number of $400 tickets sold is 30 .

Let the no of $400 be x,$200 be 4x,100 be 380+4x.
86000=400(x)+200(4x)+10(380+4x)

The answer is 30

Let the number of ticket sold with $400 is x,
$200 is y,
$100 is z

The number of $200 tickets sold is 4 times that of $400 tickets

This means y = 4x

The number of $100 tickets sold is 380 more than that of $200 tickets

This means z - y = 380
or z = 380 + y

The total income from the tickets is $86000

This means 400*x+200*y+100*z = 86000
Tidy this up 4x + 2y + z = 860

So we have three formulae:

y = 4x 1st
z = 380 + y 2nd
4x + 2y + z = 860 3rd

Put the 1st and 2nd formulae into the 3rd formula:

y + 2y + 380 + y = 860
4y +380 = 860
4y = 480
y = 120

now put the answer back into the 1st formula:

y = 4x
120 = 4x
x = 30

Therefore 30 tickets sold for $400 tickets