22' x 24' for a garage

A 22'X24'X4" slab with 24" footers and one beam would be approx. 11 yards of concrete.

Depending on your location the cost per yard can be $85 to $120 with a 10 yard minimum. You can usually figure needing at least an additional 10% to cover shortage.

Need more info such as is there a footer or thicken slab edge? Most accurate answer would come by getting 3 free bids from local contractors. I think you are in the $2500 - $3000 ball park