This iPad, Android, IWB compatible teaching resource is a variation on this one except it is much easier, perhaps too easy. This one is from this book, the follow up to the book that the previous resource was in and can be found here.
Simply swap the numbers around until they add up to 14 on each of the big circles. The problem with this as a problem is that with so few numbers and combinations it is quite solvable by trial and error rather than maths but it may be of use for younger children. Either way expect a fairly quick solution.
This resource should work on all modern browsers on computer, tablet and phone.
Go to learning resource.