--Answer--
1. $85
2. $15
--Explanation--
1. 15% off of 100 just means moving the decimal in 15 over by 2 to the left.
From there, multiply 100 x 0.15.
Then you get 15, so that's how much tax you are paying. Meaning Subtract 15 from 100 to get the price it originally was before tax. 100 - 15 = 85.
2. $15 dollars tax from moving decimal 2 to the left of 15%.
Answer: No solution
Step-by-step explanation:
I would recommend "Introduction to Linear Algebra," by Gilbert Strang. It is a compact but very helpful textbook reference written by a well-known MIT professor. There is a corresponding online MIT course that is free, so that's a bonus. I am currently using it to study linear algebra with no class or previous experience, and I think it does a solid job of explaining things. Each section in the book has a set of questions for you to work through, and answers to selected questions appear in an appendix at the end of the book.
Hope this helps!
