Answer:
The equation needed is
The cost per ream of paper = $4
Step-by-step explanation:
Here, the cost of 5 reams of paper = $ 21
The tax on her purchase = $1
So, the actual cost of 5 reams of paper = Total Cost paid - Tax amount
= $ 21 - $ 1 = $20
So, the actual cost of 5 reams of the paper is $20.
Now, to find out the cost of 1 ream of paper:
= $4
Hence, the cost of each ream of paper = $ 4.