Answer:
6 1/4 cups of flour
Explanation:
24/2 = 12
2.5/2 = 1.25
12 x 5 = 60
1.25 x 5 = 6.25 cups
For every 24 cookies Markes needs 2.5 cups of flour. So, for 12 cookies he needs half of that which is 1.25 cups. 12 is a fifth of 60, so we multiply 1.25 by 5 which gives us 6.25 cups of flour. :D