Let's denote the cost of each shirt before the discount as "x".
If you buy 4 shirts, and $10 is taken off the total cost, then the equation can be set up as:
4x - $10 = $54
Simplifying the equation:
4x = $54 + $10
4x = $64
Dividing both sides by 4:
x = $16
Therefore, each shirt was originally priced at $16 before the discount.