Joanne bought 3 baseball cards for $160. if the first card was as expensive as the combined price of the second and the third cards, and the second card cost $20 more than the third card, what is the price of the first card?

Let the price of the 3rd card be c. Now we can write the equation:
c + (c + 20) + (c + c + 20) = 160 (1)
Simplifying the left hand side of equation (1), we get:
4c + 40 = 160 (2)
Subtracting 40 from both sides of equation (2) gives:
4c = 120
from which c = $30.
Therefore the price of the second card = 30 + 20 = $50
and the price of the first card = 30 + 50 = $80.

Where are the functions?