What is the correct answer or is it all of the above?

Write the fraction 9/50 as a decimal if needed round to the nearest hundredth

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.