Johnny has $100 in the bank and plans to deposit $15 per day. Sal has $250 in the bank and plans to withdraw $10 from the bank each day. How many days
until they have the same amount in the bank?

6 days

Step-by-step explanation:

First we have to write an expression that represents Johnny's and Sal's banking plans.

Johnny: He has an initial value of $100 and that value will increase by $15 every day. So the expression looks like: 15x + 100, where x is the amount of days it's been.

Sal: An initial value of $250 and the value will decrease by $10 everyday. The expression looks like: -10x + 250, where x is the amount of days it's been.

To find how many days they have until they have the same amount of money in the bank, we can set the expressions equal to each other and solve for x:

15x + 100 = -10x + 250

Add 10x to both sides to isolate the x on one side of the equation:

25x + 100 = 250

Subtract 100 from both sides of the equation to isolate 25x:

25x = 150

Divide both sides by 25 to find the value of x:

x = 6

Since x represents the amount of days it's been, x = 6 means that it will take 6 days for their bank accounts to have the same amount of money in them.

Hope this helps :)