First, lets see if the tiles fit evenly.....
disregarding grout lines
2 feet x 5 feet is 24 inches x 60 inches
24 is a multiple of 3 and 4
60 is a multiple of 3 and 4
so the tiles should fit evenly
8 x 3 = 24 so 8 rows
15 x 4 = 60 so 15 columns 15 x 8 =120 tiles
Check: 24 x 60 = 1440 sq inches
120 tiles x 3x4 = 1440 sq inches Check!