25 is the anwser you're looking for
Step-by-step explanation:
"Is" means equals. "Less than" means subtracted from.
28 = k - 12
Add 12 to both sides to solve for k:
k = 40
x is a variable which in math means an unknown number, since 2+2=4 the answer (If your trying to find what x is) would be x=4.