Всаду 1700 деревьев, из них 25% груши и 15% яблони. сколько других сортов деревьев в этом саду.

1,    25+15=40% яблони и груши
2.    100-40=60 % остальные сорта
3.      1700:100=17 деревьев  1 %
4.      17*60=1020 деревьев других сортов

25+15=40
1700:100=17
17×40=680
1700-680=1020 деревьев в сад

Yes, I do think that hobbies are useful for people. Doing something you enjoy helps to relieve stress and keeps you happy.
There are so many hobbies it's hard to list all of them. For example reading, traveling, drawing or photography, writing, dancing. Some people like sports.
All my family is really into reading. Also my mom does yoga twice a week. And my father likes fishing.
Yeah, definitely, I believe it is very much possible to have more than one hobby.
It's hard to say what hobbies are the most interesting. It depends on a person. But I guess the most unusual one are usually the most fascinating.
My hobbies are tennis and reading. I also like listening to music a lot.
Yeah, I have been having some of my hobbies for a long time.
I'd like to take up photography.

HEALTH.
Health is very important for human. If you haven't got a strong immunity, you'll catch a cold. If you want to be healthy, you just need follow certain rules, such as: wash your hands, take a bath twice a day, change your clothes. And you must not forget about your food. Your food has to be healthy. Don't eat crisps, don't drink soda. You have to eat vegetables, fruits. Don't bite nails, it's bad for your health. If you have such habit, you need to wean from this habit. If you want to healthy - just follow this this certain rules and everything will be OK!