Tina is saving to buy a notebook computer. She has two options. The first option is to put $200 away initially and save $10 every month. The second option is to put $100 away initially and save $30 every month. After how many months would Tina save the same amount using either option? How much would she save with either option?

The correct answers are:

It would take 5 months and she would save $250.

Explanation:

Let m be the number of months.

For the first way of saving, $200 up front and $10 each month, the expression would be

200+10m.

For the second way of saving, $100 up front and $30 each month, the expression would be

100+30m.

Setting them equal gives us the equation

200+10m = 100+30m

Subtract 10m from each side:

200+10m-10m = 100+30m-10m

200 = 100+20m

Subtract 100 from each side:

200-100 = 100+20m-100

100 = 20m

Divide both sides by 20:

100/20 = 20m/20

5 = m

It would take 5 months.

$200 up front and $10 each month for 5 months:

200+10m

200+10 (5)

200+50

250

She would save $250.