Find measure of angle KJL

Which expression is equivalent to (9x - 3 1/ + 1 3/8)

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours

What is the number 321,000,000 in scientific notation? also what is the number? ?