Question

Christiana and Marlena opened their first savings accounts on the same day. Christiana opened her account with $40 and plans to deposit $10 every month. Marlena opened her account with $25 and plans to deposit $15 every month. After how many months will their two accounts have the same amount of money? What will that amount be?

Answer 1

It will take 3 months for their accounts to have the same amount and the amount would be $70.

Explanation:

Christina: Her initial amount is $40 and each month she adds $10, so the equation would be 40+10x.

Marlena: Her initial amount is $25 and she add $15 each month, so the equation would be 25+15x

Plug both of these equations into a graphing calculator (Desmos) and look for both lines intersect.

Answer 2

After 3 months of depositing, they will have the same amount.