Valeria and Autumn are reading the same book. At the beginning of the month, Valeria was on page 20 and Autumn was on page 40. Valeria will read 20 pages per day and Autumn will read 15 pages per day. Let VV represent the page of the book that Valeria is on at the end of tt days into the month, and let AA represent the page of the book that Autumn is on at the end of tt days into the month. Graph each function and determine after how many days, t, commat, Valeria and Autumn will be on the same page of the book.

1 answer

To find out when Valeria and Autumn will be on the same page of the book, we can represent their reading progress with equations based on the information given.

  1. Valeria's Reading Progress:

    • Initial page = 20
    • Reading speed = 20 pages per day
    • After \( t \) days, her page number \( V(t) \) can be expressed as: \[ V(t) = 20 + 20t \]
  2. Autumn's Reading Progress:

    • Initial page = 40
    • Reading speed = 15 pages per day
    • After \( t \) days, her page number \( A(t) \) can be expressed as: \[ A(t) = 40 + 15t \]

Next, we need to find when both are on the same page, so we set \( V(t) \) equal to \( A(t) \):

\[ 20 + 20t = 40 + 15t \]

Now, let's solve for \( t \):

\[ 20t - 15t = 40 - 20 \]

\[ 5t = 20 \]

\[ t = 4 \]

Thus, Valeria and Autumn will be on the same page after 4 days.

Verification:

  • After 4 days:
    • Valeria's page: \( V(4) = 20 + 20(4) = 20 + 80 = 100 \)
    • Autumn's page: \( A(4) = 40 + 15(4) = 40 + 60 = 100 \)

Both Valeria and Autumn are on page 100 after 4 days, confirming our solution.

Graphing:

To graph \( V(t) \) and \( A(t) \):

  1. Valeria's Function: \( V(t) = 20 + 20t \)

    • At \( t = 0 \), \( V(0) = 20 \)
    • At \( t = 4 \), \( V(4) = 100 \)

    This is a straight line with a slope of 20, starting at (0, 20).

  2. Autumn's Function: \( A(t) = 40 + 15t \)

    • At \( t = 0 \), \( A(0) = 40 \)
    • At \( t = 4 \), \( A(4) = 100 \)

    This is also a straight line but with a lower slope of 15, starting at (0, 40).

The two lines intersect at \( t = 4 \), confirming they will be on the same page of the book after 4 days.