Question

What rule changes the input numbers to output numbers?

Answer 1

Sub all the values in as if input is the x value
A) 1-3 = -2 works
     2-3 = -1 doesnt work
B) 2-4 = -2 works
     4-4 = 0 doesnt work
C) 3-5 = -2 works
     6-5 = 1  works
     9-5 = 4  works
    12-5 = 7 works 
hence C is the answer 3x - 5