Question

The total cost of four pens and six mechanical pencils is $16.20. The cost of each pencil is 70 cents. Using an arithmetic approach, find the cost of a pen.​

Answer 1

300 cents or $3

Explanation:

Let p be the cost of one pen and m be the cost of one mechanical pencil. We can use this to set up a system of equations:

4p+6m=1620 (convert $16.20 to cents by multiplying it by 100)

m=70

We can solve this using substitution (substitute 70 for m):

4p+6(70)=1620

4p+420=1620

Subtract 420 from both sides

4p=1200

Divide both sides by 4

p=300 cents or $3