What is the value of k in the function ƒ(x) = 112 - kx if ƒ(-3) = 121? k =

Plug -3 into the function to get 112+3k=f(-3)=121.
So now can calculate k: 112+3k=121, 3k=9, k=3.

Ok to solve for k, take the function f(x) = 112 - kx plug in the x value, so that would be f(-3) now we know that f(-3) = 121 so how to solve for k is quite easy. In replace f(-3) with 121 and x with -3
so 121 = 112 - k(-3) 
solve for k
subtract 112 from both sides
so that would give you 9 = -k(-3)
use the distributive property on -k(-3)
so that would be 3k = 9
divide both sides by 3
which gives you the answer k=3