Question

Briana has 4 1/2 cups of oats. She uses 2 1/4 cups of oats to make oatmeal- raisins cookies, then borrow 1 cup of oats from her neighbor. Her recipe for granola calls 2 1/2 cups of oats. Does she have enough? How much will she have left over, or how much more will she need?

Answer 1

She has enough with
`(3)/(4)` cups left over.

Explanation:

For this equation, it's probably easiest to use improper fractions.

At the start, she has 4
`(1)/(2)` cups, or
`(9)/(2)`, which can be converted to
`(18)/(4)` (which is useful for the next part) by multiplying the numerator and denominator by 2.

When she uses 2
`(1)/(4)` cups, which can be converted to
`(9)/(4)`. When subtracting this from the original, you get
`(18)/(4)`-
`(9)/(4)`=
`(9)/(4)`.

She borrows another cup, or
`(4)/(4)` of a cup, which gets added on to the previous result, giving
`(9)/(4)`+
`(4)/(4)`=
`(13)/(4)`.

The recipe calls for 2
`(1)/(2)` cups, which can be converted to
`(5)/(2)` or
`(10)/(4)`.

`(13)/(4)`-
`(10)/(4)`=
`(3)/(4)`, meaning she has
`(3)/(4)` cups left over.

** solving this mainly uses conversion to improper fractions and adding/subtracting fractions, which may be skills you would like to practice. I'm always happy to help!