Answer:
The equation
could be used to represent this situation.
Step-by-step explanation:
Given:
Azul bought 10 reams of paper at the store for a total cost of $84 the tax on the purpose was $4.
Now, to find the equation that could be used to represent this situation.
Let the cost of a ream of paper be 
Total reams of paper = 10.
The tax on the purpose = $4.
The total cost = $84.
Now, to write an equation to represent this situation:


Therefore, the equation
could be used to represent this situation.