Ma. gartlans bought x number of shirts for the new members of her chorus. the cost for x number of shirt ,including $3.99 shipping ,was 77.49. each shirt cost $12.25. there was no sales tax on the purchase

Gartlans bought X number of shirt for $12.25 each, so the total cost of the shirts 
is 12.25*X.
Now add the shipping cost like this: 12.25X+3.99.
Since the total cost was 77.49, we get the equation:


Gartlans bought 6 shirts