Does anyone know the answer to this question I've been working on it for an hour its driving me crazy

Question

Madeline has two different candles made by two different companies. The length (in centimeters) of the first candle depends on its burning time t (in hours) according to the formula f(t)=20-1.5t. The length (in centimeters) of the second candle over time t (in hours) is displayed below in the table. 

(Candle A is the with a formula)

(Candle B is the one with the table to support its height)

1. Which candle was taller originally? Justify your answer.

Answer 1

For Candle A you substitute 0 for t, to get the height at time zero, which would be 20 - 1.5(0) = 20.

For Candle B the height decreases by 5 every 2 seconds, so if it is 20 at t=2, it is 25 at time zero.

So candle B was taller originally.

Answer 2

We can set up the table as a formula as well by calculating the slope using 2 points:

m = rise/run = y2-y1/x2-x1 = 15-20/4-2 = -2.5

now we need to find the y-intercept of the table by using the slope intercept formula

y=mx+b

20 =2*-2.5+b so b=25

lets compare f(t) = 20-1.5t to s(t) = 25-2.5t at t=0 or before the candles started burning. Since f(0)=20 and s(0)=25, the candle with the table was initially longer