Alexandra was given a gift card for a coffee shop. Each morning, Alexandra uses the card to buy one

Alexandra was given a gift card for a coffee shop. Each morning, Alexandra uses the card to buy one cup of coffee. The original amount of money on the gift card was $45 and each cup of coffee costs $2.50. Write an equation for A(x),A(x), representing the amount money remaining on the card after buying xx cups of coffee.

We start with 45, and each cup of coffee decreases our balance by 2.50, so we subtract:
A(x) = 45 - 2.50x