If the number in the tenths place is 5+, you add one to the number in the hundredths place and replace all the numbers after it with 0. If the number in the tenths place is below 5, keep the number in the hundredths place the same and replace all the numbers after it with 0.
8 cookies cost $12 you divide 12 by 8 and then you get 1.5 which equals 1.50 so each cookie is 1.50. So for 10 cookies you multiply 10 times 1.50 and you get your answer $15. 10 cookies cost $15
The rest of calculation is same..
