If they ordered 3 times as many pencils as pens, how many pens and pencils did they order?

Question

An office ordered $500 worth of pens and pencils. A pencil costs 50 cents and a pen costs $1. If they order 3 times as many pencils as pens, how many pens did they order altogether? What are the steps I would take to solve this??

Answer 1

x = number of pencils at $0.50 each

 

y = number of pens at $1.00 each

 

x = 3y  [given]

 

($0.50)x + ($1.00)y = $500

 

($0.50)(3y) + ($1.00)y = $500

 

Solve for y.

 

y = 500/[3(0.50) + 1.00] = 200

x = 3y = 3(200) = 600

 

600 pencils

200 pens