Solve by logic/reasoning or trial and improvement OR USE ALGEBRA
use as a worksheet or cut into strips or individual puzzles so each student gets a different question(s)
DIFFERENTIATE by giving students some of the numbers - see answers
Otherwise these are quite challenging.
A starting point could be giving out a blank grid and supplying the numbers and get student to fill in the numbers in the circles before trying to solve these puzzles.
Use the clip-art on your own worksheets or PowerPoints etc by overlaying text boxes. Use the questions/answers for the numbers.
I was only going to do 100 questions but ended up doing 1504 (94pages x 16puzzle per page) just to see if I could ,so sorry for the overkill!