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