Another pie question

Question

I have 3/5ths of a pie and 5 guests. I cut the remaining pie into 5 equal pieces. Only 2 guests want a piece. How much of the whole pie do I have left?

Answer 1

***If you're having trouble with this problem, it could be helpful to draw out the different slices of the pie to visualize it better!***

You start with 3/5. You have 5 guests, so lets divide the 3/5 into 5 parts so they each get a piece. Mathematically, this is written as:

(3/5)/5

Dividing is the same thing as multiplying by the reciprocal, so we can rewrite this as:

(3/5) • (1/5) = 3/25.

This means that each slice is now 3/25 of the original whole pie.

Only two guests want pieces. Remember that you have 5 slices total, and each slice is 3/25. If you give away two 3/25 slices, you are giving away a total of 6/25:

(3/25) + (3/25) = 6/25

To find the amount of pie you have left, take the amount you started with and subtract the amount you gave away:

3/5 - 6/25

Create common denominators and solve.

15/25 - 6/25

= 9/25

You have 9/25 of the whole pie left.