Is x^2-8x+64 a perfect square trinomial

Yesterday i ran 5 miles. today, i ran 3.7 miles. did my percent increase, decrease or is it a percent error? plz i need

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?