Me with this algebra problem. you : )

To solve this problem you must apply the proccedure shown below:

 1. You must make a system of equations, as below:

 2. Let's call:

 x: the number of first class tickets bought.
 y: the number of coach tickets bought.

 3. Then, you have:

 x+y=7 (First equation)
 970x+370y=3790 (Second equation)

 x=7-y

 4. By substitution, you have:

 970x+370y=3790
 970(7-y)+370=3790
 y=5

 x=7-y
 x=7-5
 x=2

 Therefore, the answer is:

 - Number of first class tickets bought=2

 - Number of coach tickets bought=5
 

The answer is c drawing a