Question

you need to buy some pencils and an eraser. You can spend no more than $5. The eraser costs $1 and the pencils cost $0.25 each

Answer 1

Answer: The answer is 1.25

Step-by-step explanation: 1+0.25=1.25

Answer 2

Let E be the number of erasers and P the number of pencils, the cost for the erasers will be 1*E and the cost of the pencils will be 0.25*P.

Then, adding both, we get the total cost:

`C=E+0.25P`

If the total cost has to be 5 or less, we can define the inequality as:

`\begin{gathered} C\le5 \\ E+0.25P\le5 \end{gathered}`

We can solve this inequality as E in function of P or viceversa.

`\begin{gathered} E+0.25P\le5 \\ E\le5-0.25P \end{gathered}`
`\begin{gathered} E+0.25P\le5 \\ 0.25P\le5-E \\ P\le(5-E)/(0.25) \\ P\le20-4E \end{gathered}`

Answer:

Being E the number of erasers and P the number of pencils, the inequality is E+0.25P<=5.

The inequality for E in function of P is E<=5-0.25P.

The inequality for P in function of E is P<=20-4E.