stephanie has a recipe that calls for 2/3 tablespoons of vanilla to make 3 1/2 dozen cookies how many tablespoons of vanilla are needed per dozen cookies

The total amount of dozen cookies =

Stephanie requires to make

Let assume that:

Then; we can equate both equations together as follows:

=  

x tablespoon = 1 dozen cookies

By cross multiply and making (x) the subject of the formula, we have:

Therefore, the amount of tablespoons Stephaine will need to prepare a dozen cookies is:

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4 / 21 spoonful of vanilla

Step-by-step explanation:

3 1/2 dozens = 42 cookies

Let x = spoonful of vanilla for 1 dozen of cookies

2/3 : 42 cookies

x : 12 cookies

2/3 ÷ 42 = x ÷ 12

2/3 × 1/42 = x / 12

2 / 126 = x / 12

Cross product

2*12 = 126*x

24 = 126x

Divide both sides by 126

x = 24 / 126

= 4 / 21

x = 4 / 21 spoonful of vanilla

Per dozen of cookies requires 4/21 spoonful of vanilla

Check:

4/21 per dozen × 3 1/2 dozens

4/21 × 7/2

28 / 42

2/3 spoonful for 3 1/2 dozens

Add 225/4 to x^2 + 15x.

Step-by-step explanation:

Take the coefficient of the middle term, 15.

Now divide it by 2, 15/2.

Square that, 225/4.

Add 225/4 to x^2 + 15x.