F(x) = 112 - kx
f(-3) = 121
f(-3) = 112 - k(-3)
f(-3) = 112 + 3k
121 = 112 + 3k
121 - 112 = 3k
9 = 3k
9/3 = k
3 = k <===
<h3>Solution :</h3>

By cross multiply, we get






Therefore, answer is 
12ab will be the right answer.
Since 24a^3 = 12ab(2a^2)
And 36ab^2 = 12ab(3b)
We can write,
1 3/4 as 7/4 & 3 1/2 as 7/2
So, 7/4 + 7/2 = 21 / 4 in fraction form.
OR 5 1/4 in mixed form.