Question

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

Answer 1

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:
$12.25x+3.99=77.49\\\text{Solving the above equation for x we get:}\\x=\frac{77.49-3.99}{12.25}=6$

Gartlans bought 6 shirts