Answer:
3x + 4y
Explanation:
You need to explain more. If you are asking for an equation, x represents the cost of each notebook and y represents the cost of each pack of markers. Also, you did not mention how much each pack of of marker costed, so I used y to substitute that amount. If you do know how much a pack of markers costs, multiply that number by 4 and your new equation will be 3x + (whatever the product is).