Another problem I'm having trouble with (and please explain the answer)

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

Pleting the square f the given find the x-intercepts of the parabola with vertex (-5,13) and y-intercept (0, 12). write your answer in this form: (14,.99). if necessary, round to the nearest hundredth. *- h enter the correct answer, de verter, and ametry 00000 done doo

The deepest part of the swimming pool is 12 feet deep.the shallowest part of the pool is 3 feet deep.what is the ratio of the deeply of the deepest part of the pool to depth of the shallowest part of a pool?