The full pizza is 12 pieces. Divide 12 by 4 to find out how much she ate on Thursday. 1/4 of 12 is 3 so she ate 3 slices on Thursday. Subtract 3 from 12 to find out how much was left for the next day. There were 9 slices the next day. Next, divide 9 by 3 to find out what 1/3 of 9 is. 1/3 of 9 is 3 so subtract 3 from the 9 slices. 6 slices are the original pizza remain.
