John opens a savings account with an initial deposit of $2000. He deposits $35 each week. Mary's savings account is represented by the function y = $45x + $2800 , where y is the balance of Mary's savings account after her initial deposit and a number of weekly deposits, x. Which statement BEST compares the rate of change for the two accounts?
A . Mary deposited $800 less than John.
B. John deposits $10 more each week than Mary.
C. John deposits $10 less each week than Mary.
D. Mary deposits $7 for every $9 John deposits.
.
.
.
The rate of change represents how the balance of the savings account is changing over time. In the case of John's account, he deposits $35 every week, so the rate of change for his account is $35 per week. In the case of Mary's account, the rate of change is given by the coefficient of x in the equation y = $45x + $2800, which is $45.
The statement that best compares the rate of change for the two accounts is therefore:
D. Mary deposits $7 for every $9 John deposits.