Which of the following represents a function?

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

Assume that y varies inversely with x. if y=1.6 when x=0.5 find x when y=3.2

Shannon mary and john earn a weekly allowance ahannon earns the amount that is 2/3 of what john earns mary earns an amount that is 1 2/3 of what johns earns 20 dollars a week who eaens the greatest allowance and who earns the least