We either need to see a picture of this and/or get more information about the measurements of the triangle. In general, the area outside of the triangle will be the area of the semi-circle minus the area of the triangle itself, or: 1/2*49*3.14 - 1/2 b*h of the triangle. That first part, which is the area of the semi-circle, works out to 76.93 So based on the info we have, it becomes 76.93 - 1/2*b*h of the triangle = area outside of triangle.
If they saved £29 all together, and if each of them saved the same amount,
then each saved £29/4 = £7.25 or £7 and 25p.
(Before decimalization in 1971, £7.25 would have been £7 and 5s .)