Aubrey has three quarters of a gallon of milk to use for two recipes. She uses 1/12 of the milk for one of the recipes. How much milk does she use?

Question

i am not quite sure how to teach my son how to do this question.

Answer 1

How much milk does she use? 

She uses 1/12 of the milk.  She has 3/4 gallon of milk.

 

What is 1/12 th of 3/4 gallon?             [note: "of" usually means multiply]

 

(1/12)*(3/4) = 1/16         [cancel or reduce]

 

She uses 1/16th of a gallon of milk.

Answer 2

3/4 - 1/12 of the 3/4

 

Of means multiply so what's left is 3/4 - 3/48 which equals 3/4 - 1/16; now

we get a common denominator, so we have 12/16 - 1/16 = 11/16 gallons of milk remaining.

 

In the above, 3/4 was UNREDUCED by multiplying by 4/4 in order to get the common denominator, and 3/48 was obtained by dividing numerator & denominator each by 3, REDUCING to 1/16 for the subtraction.