What is the unknown of the following problem, "A train travels from Chicago to Pittsburg at an average speed of 85 miles per hour while another train travels from Pittsburg to Chicago at an average speed of 60 miles per hour. How much time would pass until they meet?"

step-by-step explanation:

i think 5 miles per hour

step-by-step explanation:

step-by-step explanation:

we have

using a graphing tool

see the attached figure

this is a quadratic equation (vertical parabola) open up

the vertex is a > vertex

the domain of the function is all real > interval (-∞,∞)

the range of the function is the > [-6.125,∞)

the function has two x->   and

the function is increasing over the > (0.25,∞)

the function is decreasing over the > (-∞,0.25)