4. A video rental store rents movies at $3.95 for the first night, plus $1.25 for each additional night. When you return your movie, you pay $7.70. How many extra nights did you keep the movie?

3 nights

Step-by-step explanation:

Set up an equation that represents the problem:

y = 1.25x + 3.95

Where y is the total cost and x is the number of additional nights you rent the movie

Substitute:

7.70 = 1.25x + 3.95

Subtract 3.95 on both sides:

7.70 = 1.25x + 3.95

-3.95 - 3.95

3.75 = 1.25x

Divide by 1.25 on both sides:

3.75 = 1.25x

/1.25 / 1.25

3 = x

Therefore, you kept the movie for 3 additional nights.