Well 9x40 would be the solution, so what is 9x40? That will be your answer.
2
3
−
4
2
+
9
−
4
Step-by-step explanation:
You just need to plug those expressions inside the formula: it doesn't matter if they're expressions involving a variable instead of plain numbers: the formula becomes

If you want, you can simplify it by expanding the square and then multiply the two parenthesis:

Answer:
Change per week: $20
Starting amount of money: $550
Step-by-step explanation:
<u>Given equation</u>:

where:
- x = number of weeks
- y = total account balance
<u>Change per week</u>
As the variable x represents the number of weeks, its coefficient represents the change per week in the amount of money.
Therefore, the change per week in the amount of money in the account is $20.
<u>Initial Balance</u>
The starting amount of money in the account (initial balance) will be the value of y when x = 0:

Therefore, the starting amount of money in the account is $550.