Dahlia bought Granny Smith and macintosh apples at the grocery store. The Granny Smith apples were 1.35 each if you bought 6. find the cost of each macintosh Apple is the total cost is $15 and she bought 6 of each.
Let's find the cost of the Granny Smith apples first. The total cost of the Granny Smith apples is 6 * $1.35 = $<<6*1.35=8.10>>8.10.
Since the total cost of both types of apples is $15 and the cost of Granny Smith apples is $8.10, the cost of the macintosh apples is $15 - $8.10 = $<<15-8.10=6.90>>6.90.
Now we can find the cost of each macintosh apple by dividing the total cost by the number of apples purchased, which is $6.90 / 6 = $<<6.90/6=1.15>>1.15. Answer: \boxed{1.15}.