The question sese that you enter a number in each circle so that the number on each line equals the sum of the numbers at each end.

So before you start.In the question there are three numbers 10,16,18 and there are three more numbers to fill in so you have to use two numbers that equal 10,16,18 for all of them.

For 10 I did 6+4=10 that worked for 16 I did 12+4=16 that also worked and for 18 Idid 12+6=18 and that worked.

I was luckey that I got it right the first time because on other sheets I had to do it 3 or 4 times.