What number is half way between 17 and 18

Ateacher noticed 5/8 of the students were wearing either blue shorts or white shorts. write two different ways this could be done.

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

Find the magnitude, correct to two decimal places, made by each of the following with positive direction of the x axis a) y= x the answer is 45° but i don’t know how