Answer :
Jenna has 11 markers because you add 4+7 to get 11. So Jenna has 11 markers.
Jenna has 11 markers.
This is because Even has 7 markers less than Jenna. We know that he has 4 markers, so it would be 11.
Still confused? Look at it this way. what is 7 less than 11? 4!
Or you can do 7+4
Hope I helped:)
Please tell me if I need to re-explain, I won't mind if you want me to.