Can someone me with this question?

Which math sentence can be used to determine if the triangle is a right triangle?

What is the value of m in the equation 1/2 m - 3/4n=16 when n=8

Find the measure of angle y. round your answer to the nearest hundredth. ( type the numerical answer only) a right triangle is shown with one leg measuring 5 and another leg measuring 14. an angle across from the leg measuring 5 is marked y degrees. numerical answers expected!