Answer: [tex]A = 15 - 4x[/tex] .
Step-by-step explanation:
Total amount remaining = Initial amount in the card-( Cost per cup × (Number of cups) )
Each cup of coffee costs $1.50 and after buying 4 cups of coffee, the card had a $9 remaining balance.
i.e. 9 = Initial amount in card - (1.50 × 4)
⇒ 9 = Initial amount in card - (6)
⇒ Initial amount in card = 9+-6 =15
⇒ Initial amount in card = $15
Let A be the amount money remaining on the card after buying x cups of coffee.
So, A = 15 - 4x
Hence, the required equation is [tex]A = 15 - 4x[/tex] .