Question

Julio and David were in Target and decided to check out the clearance section. They found pencils and erasers that were on sale and decided to buy some. Julio bought 4 pencils and 3 erasers for $0.37 and David paid $0.33 for 3 pencils and 4 erasers. What is the cost of one pencil? What is the cost of one eraser?

Answer 1

Cost of one pencil:
`\$0.07`

Cost of one eraser:
`\$0.03`

Explanation:

Let be "p" the cost in dollars of one pencil and "e" the cost in dollars of one eraser.

Based on the information given in the exercise, you can set up the following system of equations:

`\left \{ {{4p+3e=0.37} \atop {3p+4e=0.33 }} \right.`

You can use the Elimination Method to solve the system of equations.

Multiply the first equation by -3 ad the second one by 4. Then add the equations and solve for "e":

{
`\left \{ {{-12p-9e=-1.11} \atop {12p+16e=1.32}} \right.\\..........................\\7e=0.21\\\\e=0.03`

Substitute the value of "e" into any original equation and solve for "p":

`4p+3(0.03)=0.37\\\\p=(0.28)/(4)\\\\p=0.07`