Question

Hi, could you explain how to solve this problem? (thankx!):

The price of a certain item was $10 in 1990 and it has gone up by $2 per year since 1990. If this trend continues, in what year will the price be $100?

Answer 1

Could you try translating the problem into an algebra expression? (I'll help if you need it :) )

Answer 2

Sure

Answer 3

This doesn't make any sense, but the only thing I can think of is: (x+2)+10

Answer 4

Close. We start out with $10, that's constant. We add $2 every year, so instead of adding x+2, you'll mutiply, so you have 10+2x

Answer 5

Oh, okay. I'm a little confused, though - why would you do 2 MULTIPLIED by x - isn't that saying that the amount DOUBLES?

Answer 6

Good question, that means that you add 2 more dollars every year. So after one year, you will have 10+(2)(1), or $12. After 2 years you have 10+(2)(2), or $14

Answer 7

OH, I see! Okay, that makes a lot of sense!

Answer 8

Great! So now you want to find how much time it takes to have $100.

Answer 9

Okay, that would take 45 years.

Answer 10

Right. Now you just have to add that on to 1990 and you'll have the year you get $100

Answer 11

And that turns out to be the right answer!

Answer 12

2035

Answer 13

:)

Answer 14

Yay! Thanks so much - you've been really helpful!

Answer 15

You're welcome, good luck

Answer 16

:)