Okay, think of it as a pie. They ate 3/4 of the pie, leaving 1/4. Then that 1/4 was cut into 6/6, and 1/6 was eaten. So there were 5/6 left of that 1/4. Your pie has 4 quarters, and each is made up of 6 mini pieces, so 6 x 4 = 24. There were 24 little 1/6 pieces at the beginning when your lasagna pie was whole. Now, at the end, you have 5 of them left. So you have five of the original 24—[tex] \frac{5}{24} [/tex].
