Apples are on sale at the grocery store at a price of 8 apples for $4.00 .mark buys 12 apples. if he is charged the sale price for apples, how much will mark pay?

You can do this problem 2 ways.  Whichever works easier for you:

Take the cost of 8 apples and divide it by 8 in order to find a per apple cost
4/8 = $.50 per apple
Then multiply the total number of apples by the cost per apple
12 * $.50 = $6.00 paid

Or

You can divide the total number of apples by 8 to find how many units of apples you have

12/8 = 1.5

Then multiply the number of units by the cost for 1 unit (8 apples)

1.5*$4 = $6.00