Thomas has constant speeds for both running and walking. When a down-escalator is moving, Thomas can run down it in 15
seconds or walk down it in
30
seconds. One day, when the escalator was broken (and stationary), it took Thomas
20
seconds to run down it.

How long, in seconds, would it take Thomas to walk down the broken escalator?

options a,b,c are the right answer.

step-by-step explanation:

a linear parent function is always represented as y = x

if we write this function in the form of y=mx+c

⇒

or  

now if we plot a graph we will find these characteristics:

1) y intercept of the graph is zero so its a straight line passing through origin.

2) as we can see in both the forms of function written, values of x and y may be either positive or negative for the positive slope means points on the graph are either in first quadrant or in third one.

3) it's slope is one.

answer: it's d

step-by-step explanation: