algebra problem

let's assign variables

 

Adults= A    Children=C

 

We know that an adult cost 4$ so 4A

We know a kid cost 2$ so 2C

 

We know that 2C+4A= 6400

 

We know that there are A number of adults and C number of children

 

So, we know C+A= 2000

 

multiply it by two so that we can subtract the two equations.

 

We can subtract these two equations. 

 

2c+4a=6400

-2C+2A=4000

 

2A=2400

--     ------

2        2

 

A=1200

 

Plug it into either of the equations

 

C+1200=2000

C=800

 

1200 Adults and 800 children

2000 tix total

a = adult        Value = $ 4a

c = child     =  2000 - a          Value  $2 (2000-a)      Summed = $ 6400

4a    +   2(2000-a) = 6400       Solve for 'a'      Then    c = 2000-a