Solve the equation. check the solutions 32 – 16^2k^2 = 0

a. {4/9}

b. {-4/9}

c. {-4/9,4/9}

d. {-9/4,9/4}

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?