How many $5 bills did hermione have in her purse?

Let x=the number of $1 bills she has, and let y=the number of $5 she has. From the information given, we can say:

x+5y=40

x+y=12

When you subtract the first equation from the second equation, you get:

x+5y-x-y=40-12

4y=28

y=7

Therefore, Hermione has 7 $5 bills in her purse.

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation: