Help me with this please

Seth practice piano for 1 1/3 hours on saturday and 5/6 hour on sunday for much longer did he practice on saturday than on sunday?

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Solve: 25 points find the fifth term of an increasing geometric progression if the first term is equal to 7−3 √5 and each term (starting with the second) is equal to the difference of the term following it and the term preceding it.