Question

Brian needs $315 to buy a new cell phone. He has already saved $115 and plans to save an additional

$10 per week. He also needs to pay off the balance on his current phone, which is $140. How many
weeks will he have to save to buy the phone?

Answer 1

34 weeks

Explanation:

Hello!

We can set up an equation to solve for the number of weeks.

Let w = the number of weeks he is saving up.

The equation is
`315 = 115 + 10w - 140`

• 315 is the target amount
• 115 is the current amount
• 10w is the rate of growth
• 140 is the current debt

Solve for w

• 
  `315 = 115 + 10w - 140`
• 
  `315 = -25 + 10w`
• 
  `340 = 10w`
• 
  `340/10 = w`
• 
  `34 = w`

He needs to save up for 34 weeks.