Let \( x \) represent the number of days that have passed.
The number of listens for the first song after \( x \) days can be represented as: \[ 1000 + 38x \]
The number of listens for the second song after \( x \) days can be represented as: \[ 900 + 40x \]
To find the number of days it would take for the two songs to have the same number of listens, we need to set the two expressions equal to each other: \[ 1000 + 38x = 900 + 40x \]
This is the equation that can be solved for \( x \) to determine the number of days until the listens are equal.