The question says" different rectengular formations"
t:8-s:30, t:10-s:24, t:12-s:20, t:16-s:15, t:20-s:12, t:24-s:10, t:30-s:8
I think the answer is 4 bec. t:8-s:30 and t:30-s:8 have the same formations as well as t:12-s:20, t:20-s:12 and t:10-s:24 t:24-s:10.