What formula could I use to solve this ?
Using f(x) =-3+7
What is x when f(x) = -20

x = 9

Step-by-step explanation:

I think you wrote the question wrong (I am assuming that there is a x next to the -3).

Subtract 7

-27 = -3x

divide by -3

9 = x

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.

i think the correct option is the second option.