Question

a school bake sale earned over $25 from selling cookies, which cost $3 each. how many cookies did they sell? identify the number that are include in the solution set

Answer 1

It said the sale earned OVER $25 from selling cookies at $3 dollars each so if we let r=revenue , p=price per cookie and c=number of cookies sold:

pc>r  and since p=3 and r=25 

3c>25  divide both sides by 3

c>25/3

Since cookies are quantized units, they must be integers so:

c>8 1/3

c≥9  or in interval notation

c=[9, +oo)