What is 0.69 expressed as a fraction in simplest form?

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Afarm that has 4 x 10^2 acres has 1.2 x 10^5 cattle. what is the average number of cattle per acre? write the answer in scientific notation. answere asap

Alicia puts $400 in a bank account. each year the account earns 5% simple interest. how much money will be in her bank account in six months?