How could you use products to check the solution to this proportion

Item 8 an account earns simple interest. $700 at 8% for 6 years a. find the interest earned. $ b. find the balance of the account. $

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?

Can you me with this question? i'll reward *30 points i just need with this one question so that i could solve the others. * edit: i originally set up the question to reward 30 points, but for some reason i can only reward 15. if you don't get 30, then i'm sorry. i'm still kind of new to this site