Question

Tina is saving to buy a notebook computer. She has two options. The first option is to put $400 away initially and save $20 every month. The second option is to put $100 away initially and save $40 every month. After how many months would Tina save the same amount using either option? How much would she save with either option?

Answer 1

Answer:

The first option is to put $400 away initially and save $20 every month. Let she saves for x months. Equation becomes;

$400+20x$

The second option is to put $100 away initially and save $40 every month.  Let she saves for x months. Equation becomes;

$100+40x$

Equating both as equal we will get the number of months.

$400+20x=100+40x$

=> $40x-20x=400-100$

=> $20x=300$

x = 15

Hence, it will take 15 months to save the same amount.

And amount saved will be = $400+20(15)$

= $700

Answer 2

1st month: $100 + 40 = 140 | 400 + 20 = 420
2nd month: 180 | 440
3rd month: 220 | 460
4th month: 260 | 480
5th month: 300 | 500
After five months, the distance between the amount of money saved has decreased by $100. 5 x 3 = 15, therefore the amount of money saved will be the same after 15 months. 

Hope this helps!

Ash