Algebra
posted by mimi .
The attendance at a baseball game was 400 people. Student tickets cost $2 and adult tickets cost $3. Total ticket sales were $1050. How many tickets of each type were sold?
Instructions: Write an equation to model each situation.
Can someone please tell me HOW to do this and WHY each step is taken?

The attendance at a baseball game was 400 people. Student tickets cost $2 and adult tickets cost $3. Total ticket sales were $1050. How many tickets of each type were sold?
1S + A = 400
22S + 3A = 1050
32 x (1) yields 2S + 2A = 800
4Subtract (3) from (2) yieldingA = 250
5It follows that S = 150 
200 student tickets and 200 adult tickets