Question

Amir is starting a stamp collection. After 3 weeks he has collected 35 different stamps, and after 9 weeks he has collected 105 different stamps. If Amir keeps collecting stamps at this same rate, how many stamps will he have after 15 weeks?

Answer 1

He will have 175 stamps after 15 weeks of collecting stamps

Explanation:

I just used this and it was correct

Answer 2

He will have 175 stamps after 15 weeks

Explanation:

After 3 weeks he has collected 35 different stamps

(3,35)

After 9 weeks he has collected 105 different stamps

(9,105)

We are given that supposed to find how many stamps will he have after 15 weeks

Formula :
`y-y_1=(y_2-y_1)/(x_2-x_1)(x-x_1)`

`(x_1,y_1)=(3,35)\\(x_2,y_2)=(9,105)`

Substitute the values in the formula :

`y-35=(105-35)/(9-3)(x-3)`

`y-35=(35)/(3)(x-3)`

`3y-105=35x-105`

`y=(35)/(3)x`

y is the no. of stamps

x is the no. of weeks

Substitute x =15

`y=(35)/(3)(15)`

`y=175`

Hence he will have 175 stamps after 15 weeks