Question

two classmates have decided to read all the volumes in a popular series of books. Katie has already read 4 volumes and will continue to read new ones at the rate of 1 volume per week. Maria, who hasn't started reading the series yet, will read 3 volumes per week. At some point, Marina will catch up with Katie and they will be reading the same book. How long will that take? How many volumes will each girl have read by then?

Answer 1

To solve this we can make it into an equation, which looks like this

y = 2x (for Rebecca)
y = x + 10 (for Alice)

The we subtract one equation from the other to solve

0 = x - 10
10 = x
x = 10

Now we replace x in whichever equation and we get 20

So, each girl will read 20 books for them to be at the same book.

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