Which of the following scenarios has a lower y-intercept than y = 4x + 5 ? (a.) a 50 gallon tub is draining. every 2 minutes, the amount of water decreases by 2 gallons. (b.) reginaldo had $17 in his account and for every book he buys, it costs him $4. (c.) sydney has collected 8 postcards. each time a friend comes to visit, sydney gives her a postcard. (d.) owen has 3 pets. he receives a new pet each time he has a birthday.

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The key to this question is "What do you start with?" All of them (except D) start with something and then a condition reduces the starting point.
A
The condition (at zero) starts with 50 gallons. Every 2 minutes the amount  taken away is 2 gallons. 
The equation looks like this
y = -2x + 50
So what do you start with? You started with 50 gallons. That's your y intercept. It's big. A is NOT the answer.

B
Renaldo starts with 17 dollars. He hasn't done anything, and he still has 17 dollars. If he buys a book, he has 4 dollars less. So his equation is
y = -4x + 17. The y intercept is 17 if he has bought no books. The answer is NOT B

C
Sydney starts with 8 postcards. Every time a friend comes, Sydney has 1 less post card. Her equation is
y = 8 - x That's not the answer either.

D
What do you start with? 3 pets, correct? Every birthday Owen get's one more. But the starting point is three. So his equation is
y= 3 + x where x is the number of birthdays.
D has the lowest starting point.

D <<<< Answer

The answer is 49/16 or 3 1/16