What is the aprproximate length of the arc formed by a 90 angle on a circle that has a radious of 70 feet

I'm confused on this could anyone me and show me what i need to do to solve it.

Jack is considering a list of features and fees for current bank: jack plans on using network atms about 4 times per month. what would be jack’s total estimated annual fees for a checking account with direct paycheck deposit, one overdraft per year, and no 2nd copies of statements? a. $44 b. $104 c. $144 d. $176

Rewrite the expression in z to the n power. the expression i was given is: 1 over z to the negative 1 half power.