It's good you're motivated. 4 hours is enough.
Looks like you need help ( you wrote help like 5 times in your post) we'll here's my 2 cents
Keep in mind you should be measuring the amount of study, not by the amount of hours, but by the tasks you have completed, i.e. quality, since you can say you studied for 4 hours when in actual fact all you achieved was create indents on your ass. Make sure you get some rest though. Sleep is the best study.
Ask your teachers how you can get 100% in the respective subject and use that as a guide, or if they're shit, do some research on your own.
You don't have to study all your subjects in one day, unless it's a weekend, so use your weekends for hardcore studying. But that'll depend on what you're aims are. Like everybody says, make a study timetable, since it will help you organise your subjects around. I personally don't use one, since I just use a to do list. But don't pressure yourself to follow it rigorously; merely use it as a guide to remind yourself of what a perfect study day would look like.
Here's what you 'I think' you should do for General maths and business
General Maths:
Get all the content down, and make sure that you're confident with all the questions and formulas. To do this, get something like excel, or maths in focus. Memorise the formulas, even though they provide you with a sheet of formulas. It saves time. After that, practice on as many past papers as you can, until you're getting 100% in every practice exam. Then get state rank. Ask your teacher for help
Business Studies:
Memorise the syllabus. Your teacher would have probably told you the syllabus is the most important thing for Business. Memorise ALL THE SYLLABI FOR THE 5 TOPICS. Then Write notes. Practice on past papers. Ask your teacher. Get State rank.
Hope that helps,
FROM YA MUM!